41 results on '"Correa-Baena JP"'
Search Results
2. The Role of Dimensionality on the Optoelectronic Properties of Oxide and Halide Perovskites, and their Halide Derivatives
- Author
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Hoye, RLZ, Hidalgo, J, Jagt, RA, Correa-Baena, JP, Fix, T, and MacManus-Driscoll, JL
- Subjects
photovoltaics ,electronic dimensionality ,perovskite‐ ,perovskites ,inspired materials ,light‐ ,emitting diodes ,structural dimensionality ,7. Clean energy ,defects - Abstract
Funder: Kim and Juliana Silverman Research Fellowship, Funder: Graduate Assistance in Areas of National Need, Halide perovskite semiconductors have risen to prominence in photovoltaics and light‐emitting diodes (LEDs), but traditional oxide perovskites, which overcome the stability limitations of their halide counterparts, have also recently witnessed a rise in potential as solar absorbers. One of the many important factors underpinning these developments is an understanding of the role of dimensionality on the optoelectronic properties and, consequently, on the performance of the materials in photovoltaics and LEDs. This review article examines the role of structural and electronic dimensionality, as well as form factor, in oxide and halide perovskites, and in lead‐free alternatives to halide perovskites. Insights into how dimensionality influences the band gap, stability, charge‐carrier transport, recombination processes and defect tolerance of the materials, and the impact these parameters have on device performance are brought forward. Particular emphasis is placed on carrier/exciton‐phonon coupling, which plays a significant role in the materials considered, owing to their soft lattices and composition of heavy elements, and becomes more prominent as dimensionality is reduced. It is finished with a discussion of the implications on the classes of materials future efforts should focus on, as well as the key questions that need to be addressed.
3. Planar Perovskite Solar Cells with High Open-Circuit Voltage Containing a Supramolecular Iron Complex as Hole Transport Material Dopant
- Author
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Saygili, Y, Turren-Cruz, SH, Olthof, S, Saes, BWH, Pehlivan, IB, Saliba, M, Meerholz, K, Edvinsson, T, Zakeeruddin, SM, Gratzel, M, Correa-Baena, JP, Hagfeldt, A, Freitag, M, and Tress, W
4. An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- Author
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T. Jesper Jacobsson, Adam Hultqvist, Alberto García-Fernández, Aman Anand, Amran Al-Ashouri, Anders Hagfeldt, Andrea Crovetto, Antonio Abate, Antonio Gaetano Ricciardulli, Anuja Vijayan, Ashish Kulkarni, Assaf Y. Anderson, Barbara Primera Darwich, Bowen Yang, Brendan L. Coles, Carlo A. R. Perini, Carolin Rehermann, Daniel Ramirez, David Fairen-Jimenez, Diego Di Girolamo, Donglin Jia, Elena Avila, Emilio J. Juarez-Perez, Fanny Baumann, Florian Mathies, G. S. Anaya González, Gerrit Boschloo, Giuseppe Nasti, Gopinath Paramasivam, Guillermo Martínez-Denegri, Hampus Näsström, Hannes Michaels, Hans Köbler, Hua Wu, Iacopo Benesperi, M. Ibrahim Dar, Ilknur Bayrak Pehlivan, Isaac E. Gould, Jacob N. Vagott, Janardan Dagar, Jeff Kettle, Jie Yang, Jinzhao Li, Joel A. Smith, Jorge Pascual, Jose J. Jerónimo-Rendón, Juan Felipe Montoya, Juan-Pablo Correa-Baena, Junming Qiu, Junxin Wang, Kári Sveinbjörnsson, Katrin Hirselandt, Krishanu Dey, Kyle Frohna, Lena Mathies, Luigi A. Castriotta, Mahmoud. H. Aldamasy, Manuel Vasquez-Montoya, Marco A. Ruiz-Preciado, Marion A. Flatken, Mark V. Khenkin, Max Grischek, Mayank Kedia, Michael Saliba, Miguel Anaya, Misha Veldhoen, Neha Arora, Oleksandra Shargaieva, Oliver Maus, Onkar S. Game, Ori Yudilevich, Paul Fassl, Qisen Zhou, Rafael Betancur, Rahim Munir, Rahul Patidar, Samuel D. Stranks, Shahidul Alam, Shaoni Kar, Thomas Unold, Tobias Abzieher, Tomas Edvinsson, Tudur Wyn David, Ulrich W. Paetzold, Waqas Zia, Weifei Fu, Weiwei Zuo, Vincent R. F. Schröder, Wolfgang Tress, Xiaoliang Zhang, Yu-Hsien Chiang, Zafar Iqbal, Zhiqiang Xie, Eva Unger, Interdisciplinary Graduate School (IGS), Energy Research Institute @ NTU (ERI@N), Helmholtz-Zentrum Berlin for Materials and Energy, European Commission, European Research Council, Ministerio de Economía y Competitividad (España), Jacobsson, TJ [0000-0002-4317-2879], Hultqvist, A [0000-0002-2402-5427], García-Fernández, A [0000-0003-1671-9979], Anand, A [0000-0001-8984-1663], Al-Ashouri, A [0000-0001-5512-8034], Crovetto, A [0000-0003-1499-8740], Ricciardulli, AG [0000-0003-2688-9912], Kulkarni, A [0000-0002-7945-208X], Coles, BL [0000-0002-1291-4403], Ramirez, D [0000-0003-2630-7628], Fairen-Jimenez, D [0000-0002-5013-1194], Juarez-Perez, EJ [0000-0001-6040-1920], Baumann, F [0000-0003-0203-5971], Mathies, F [0000-0002-8950-3901], Paramasivam, G [0000-0003-2230-0787], Näsström, H [0000-0002-3264-1692], Michaels, H [0000-0001-9126-7410], Köbler, H [0000-0003-0230-6938], Dar, MI [0000-0001-9489-8365], Gould, IE [0000-0002-2389-3548], Kettle, J [0000-0002-1245-5286], Montoya, JF [0000-0002-6236-8922], Correa-Baena, JP [0000-0002-3860-1149], Wang, J [0000-0003-3849-3835], Sveinbjörnsson, K [0000-0001-6559-3781], Frohna, K [0000-0002-2259-6154], Vasquez-Montoya, M [0000-0003-0001-8641], Flatken, MA [0000-0003-2653-4468], Khenkin, MV [0000-0001-9201-0238], Grischek, M [0000-0002-9786-4854], Kedia, M [0000-0002-4770-3809], Saliba, M [0000-0002-6818-9781], Anaya, M [0000-0002-0384-5338], Shargaieva, O [0000-0003-4920-3282], Stranks, SD [0000-0002-8303-7292], Kar, S [0000-0002-7325-1527], Unold, T [0000-0002-5750-0693], Edvinsson, T [0000-0003-2759-7356], David, TW [0000-0003-0155-9423], Paetzold, UW [0000-0002-1557-8361], Zhang, X [0000-0002-2847-7359], Chiang, YH [0000-0003-2767-3056], Unger, E [0000-0002-3343-867X], and Apollo - University of Cambridge Repository
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Materials [Engineering] ,Renewable Energy, Sustainability and the Environment ,Analysis Tools ,Energy Engineering and Power Technology ,Materialkemi ,005: Computerprogrammierung, Programme und Daten ,stability ,ACCESS Database ,Electronic, Optical and Magnetic Materials ,4017 Mechanical Engineering ,621.3: Elektro-, Kommunikations-, Steuerungs- und Regelungstechnik ,Mediateknik ,Fuel Technology ,Media Engineering ,efficiency ,Materials Chemistry ,ddc:330 ,Photovoltaics and Wind Energy ,Generic health relevance ,ddc:620 ,4008 Electrical Engineering ,light ,Engineering & allied operations ,40 Engineering - Abstract
et al., Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences., Open access funding provided by Helmholtz-Zentrum Berlin für Materialien und Energie GmbH., The core funding of the project has been received from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 787289. We acknowledge the following sources for individual funding. Cambridge India Ramanujan Scholarship, China Scholarship Council, Deutscher Akademischer Austauschdienst (DAAD), EPSRC (grant no. EP/S009213/1), European Union’s Horizon 2020 research and innovation programme (grant no. 764787, EU Project ‘MAESTRO’), (grant no. 756962, ERC Project ‘HYPERION’), (grant no. 764047, EU Project ‘ESPResSo’ and grant no. 850937), GCRF/EPSRC SUNRISE (EP/P032591/1), German Federal Ministry for Education and Research (BMBF), HyPerFORME, NanoMatFutur (grant no. 03XP0091). PEROSEED (ZT-0024), Helmholtz Energy Materials Foundry, The Helmholtz Innovation Laboratory HySPRINT. BMBF (grant nos. 03SF0540, 03SF0557A), HyPerCells graduate school, Helmholtz Association, Helmholtz International Research School (HI-SCORE), the Erasmus programme (CDT-PV, grant no. EP/L01551X/1), the European Union’s Horizon 2020 research and innovation programme (Marie Skłodowska-Curie grant agreement nos. 841386, 795079 and 840751), Royal Society University Research Fellowship (grant no. UF150033). SNaPSHoTs (BMBF), SPARC II, German Research Foundation (DFG, grant no. SPP2196), The National Natural Science Foundation of China (grant no. 51872014), the Recruitment Programme of Global Experts, Fundamental Research Funds for the Central Universities and the ‘111’ project (grant no. B17002), the US Department of Energy’s Office of Energy Efficiency and Renewable Energy under Solar Energy Technologies Office (SETO) agreement no. DE-EE0008551, the Colombia Scientific Programme in the framework of the call Ecosistema Cientifíco (Contract no. FP44842-218-2018), the committee for the development of research (CODI) of the Universidad de Antioquia (grant no. 2017-16000), Spanish MINECO (Severo Ochoa programme, grant no. SEV‐2015‐0522), the Swedish research council (VR, grant no. 2019-05591) and the Swedish Energy Agency (grant no. 2020-005194).
- Published
- 2022
5. The Role of Dimensionality on the Optoelectronic Properties of Oxide and Halide Perovskites, and their Halide Derivatives
- Author
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Hoye, Robert L. Z., Hidalgo, Juanita, Jagt, Robert A., Correa‐Baena, Juan‐Pablo, Fix, Thomas, MacManus‐Driscoll, Judith L., Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie (ICube), Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Hoye, RLZ [0000-0002-7675-0065], Hidalgo, J [0000-0002-5832-3262], Jagt, RA [0000-0002-0517-3758], Correa-Baena, JP [0000-0002-3860-1149], Fix, T [0000-0002-1531-725X], MacManus-Driscoll, JL [0000-0003-4987-6620], Apollo - University of Cambridge Repository, École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Les Hôpitaux Universitaires de Strasbourg (HUS)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Downing College, Cambridge, Royal Academy of Engineering, Royal Academy Of Engineering, and Isaac Newton Trust
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Technology ,EXCITON BINDING-ENERGY ,RUDDLESDEN-POPPER ,02 engineering and technology ,0915 Interdisciplinary Engineering ,7. Clean energy ,01 natural sciences ,[SPI.MAT]Engineering Sciences [physics]/Materials ,law.invention ,chemistry.chemical_compound ,electronic dimensionality ,law ,Photovoltaics ,EFFECTIVE IONIC-RADII ,General Materials Science ,defects ,NARROW-BAND GAP ,Chemistry, Physical ,Physics ,perovskite‐ ,0303 Macromolecular and Materials Chemistry ,021001 nanoscience & nanotechnology ,Chemistry ,Physics, Condensed Matter ,Physical Sciences ,Optoelectronics ,0210 nano-technology ,DEFECT-TOLERANT SEMICONDUCTORS ,Light-emitting diode ,Curse of dimensionality ,Materials science ,Energy & Fuels ,CHARGE-CARRIER MOBILITIES ,Materials Science ,perovskites ,Oxide ,inspired materials ,Halide ,Materials Science, Multidisciplinary ,emitting diodes ,structural dimensionality ,010402 general chemistry ,Physics, Applied ,WHITE-LIGHT EMISSION ,THIN-FILMS ,light‐ ,0912 Materials Engineering ,Science & Technology ,Renewable Energy, Sustainability and the Environment ,business.industry ,light‐ ,perovskite‐ ,0104 chemical sciences ,photovoltaics ,chemistry ,SOLAR-CELL ABSORBER ,CESIUM LEAD HALIDE ,business - Abstract
Halide perovskite semiconductors have risen to prominence in photovoltaics and light‐emitting diodes (LEDs), but traditional oxide perovskites, which overcome the stability limitations of their halide counterparts, have also recently witnessed a rise in potential as solar absorbers. One of the many important factors underpinning these developments is an understanding of the role of dimensionality on the optoelectronic properties and, consequently, on the performance of the materials in photovoltaics and LEDs. This review article examines the role of structural and electronic dimensionality, as well as form factor, in oxide and halide perovskites, and in lead‐free alternatives to halide perovskites. Insights into how dimensionality influences the band gap, stability, charge‐carrier transport, recombination processes and defect tolerance of the materials, and the impact these parameters have on device performance are brought forward. Particular emphasis is placed on carrier/exciton‐phonon coupling, which plays a significant role in the materials considered, owing to their soft lattices and composition of heavy elements, and becomes more prominent as dimensionality is reduced. It is finished with a discussion of the implications on the classes of materials future efforts should focus on, as well as the key questions that need to be addressed.
- Published
- 2021
6. Nanometer Control of Ruddlesden-Popper Interlayers by Thermal Evaporation for Efficient Perovskite Photovoltaics.
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Datta K, Kim S, Li R, LaFollette DK, Yang J, Perini CAR, and Correa-Baena JP
- Abstract
Solution-processed Ruddlesden-Popper (RP) interlayers in lead halide perovskite solar cells (PSCs) present processing challenges due to fast film formation and uncontrolled growth of phases and layer thickness at interfaces. In this work, an alternative, solvent-free, thermal co-evaporation process is developed to deposit RP interlayers. The method provides precise control on interlayer thickness and enables understanding its role on charge-carrier extraction. Studying RP film growth reveals the development of heterointerfaces when deposited on three-dimensional (3D) perovskite layers. This allows a large thickness window with an optimum between 20 nm and 40 nm to improve the optoelectronic properties of the underlying 3D perovskite. Solar cells using evaporated interlayers achieve power conversion efficiency of 21.6%, compared to 19.6% for untreated devices, driven by improvements in the open-circuit voltage and fill factor. This work sheds light on the importance of phase and thickness control of passivation layers, which ultimately determine the solar cell performance in state-of-the-art PSCs., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)
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- 2024
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7. Non-covalent planarizing interactions yield highly ordered and thermotropic liquid crystalline conjugated polymers.
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Sabury S, Xu Z, Saiev S, Davies D, Österholm AM, Rinehart JM, Mirhosseini M, Tong B, Kim S, Correa-Baena JP, Coropceanu V, Jurchescu OD, Brédas JL, Diao Y, and Reynolds JR
- Abstract
Controlling the multi-level assembly and morphological properties of conjugated polymers through structural manipulation has contributed significantly to the advancement of organic electronics. In this work, a redox active conjugated polymer, TPT-TT, composed of alternating 1,4-(2-thienyl)-2,5-dialkoxyphenylene (TPT) and thienothiophene (TT) units is reported with non-covalent intramolecular S⋯O and S⋯H-C interactions that induce controlled main-chain planarity and solid-state order. As confirmed by density functional theory (DFT) calculations, these intramolecular interactions influence the main chain conformation, promoting backbone planarization, while still allowing dihedral rotations at higher kinetic energies (higher temperature), and give rise to temperature-dependent aggregation properties. Thermotropic liquid crystalline (LC) behavior is confirmed by cross-polarized optical microscopy (CPOM) and closely correlated with multiple thermal transitions observed by differential scanning calorimetry (DSC). This LC behavior allows us to develop and utilize a thermal annealing treatment that results in thin films with notable long-range order, as shown by grazing-incidence X-ray diffraction (GIXD). Specifically, we identified a first LC phase, ranging from 218 °C to 107 °C, as a nematic phase featuring preferential face-on π-π stacking and edge-on lamellar stacking exhibiting a large extent of disorder and broad orientation distribution. A second LC phase is observed from 107 °C to 48 °C, as a smectic A phase featuring sharp, highly ordered out-of-plane lamellar stacking features and sharp tilted backbone stacking peaks, while the structure of a third LC phase with a transition at 48 °C remains unclear, but resembles that of the solid state at ambient temperature. Furthermore, the significance of thermal annealing is evident in the ∼3-fold enhancement of the electrical conductivity of ferric tosylate-doped annealed films reaching 55 S cm
-1 . More importantly, thermally annealed TPT-TT films exhibit both a narrow distribution of charge-carrier mobilities (1.4 ± 0.1) × 10-2 cm2 V-1 s-1 along with a remarkable device yield of 100% in an organic field-effect transistor (OFET) configuration. This molecular design approach to obtain highly ordered conjugated polymers in the solid state affords a deeper understanding of how intramolecular interactions and repeat-unit symmetry impact liquid crystallinity, solution aggregation, solution to solid-state transformation, solid-state morphology, and ultimately device applications.- Published
- 2024
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8. Bromine Incorporation Affects Phase Transformations and Thermal Stability of Lead Halide Perovskites.
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LaFollette DK, Hidalgo J, Allam O, Yang J, Shoemaker A, Li R, Lai B, Lawrie B, Kalinin S, Perini CAR, Ahmadi M, Jang SS, and Correa-Baena JP
- Abstract
Mixed-cation and mixed-halide lead halide perovskites show great potential for their application in photovoltaics. Many of the high-performance compositions are made of cesium, formamidinium, lead, iodine, and bromine. However, incorporating bromine in iodine-rich compositions and its effects on the thermal stability of the perovskite structure has not been thoroughly studied. In this work, we study how replacing iodine with bromine in the state-of-the-art Cs
0.17 FA0.83 PbI3 perovskite composition leads to different dynamics in the phase transformations as a function of temperature. Through a combination of structural characterization, cathodoluminescence mapping, X-ray photoelectron spectroscopy, and first-principles calculations, we reveal that the incorporation of bromine reduces the thermodynamic phase stability of the films and shifts the products of phase transformations. Our results suggest that bromine-driven vacancy formation during high temperature exposure leads to irreversible transformations into PbI2 , whereas materials with only iodine go through transformations into hexagonal polytypes, such as the 4H-FAPbI3 phase. This work sheds light on the structural impacts of adding bromine on thermodynamic phase stability and provides new insights into the importance of understanding the complexity of phase transformations and secondary phases in mixed-cation and mixed-halide systems.- Published
- 2024
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9. Tailoring Interface Energies via Phosphonic Acids to Grow and Stabilize Cubic FAPbI 3 Deposited by Thermal Evaporation.
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Castro-Méndez AF, Jahanbakhshi F, LaFollette DK, Lawrie BJ, Li R, Perini CAR, Rappe AM, and Correa-Baena JP
- Abstract
Coevaporation of formamidinium lead iodide (FAPbI
3 ) is a promising route for the fabrication of highly efficient and scalable optoelectronic devices, such as perovskite solar cells. However, it poses experimental challenges in achieving stoichiometric FAPbI3 films with a cubic structure (α-FAPbI3 ). In this work, we show that undesired hexagonal phases of both PbI2 and FAPbI3 form during thermal evaporation, including the well-known 2H-FAPbI3 , which are detrimental for optoelectronic performance. We demonstrate the growth of α-FAPbI3 at room temperature via thermal evaporation by depositing phosphonic acids (PAc) on substrates and subsequently coevaporating PbI2 and formamidinium iodide. We use density-functional theory to develop a theoretical model to understand the relative growth energetics of the α and 2H phases of FAPbI3 for different molecular interactions. Experiments and theory show that the presence of PAc molecules stabilizes the formation of α-FAPbI3 in thin films when excess molecules are available to migrate during growth. This migration of molecules facilitates the continued presence of adsorbed organic precursors at the free surface throughout the evaporation, which lowers the growth energy of the α-FAPbI3 phase. Our theoretical analyses of PAc molecule-molecule interactions show that ligands can form hydrogen bonding to reduce the migration rate of the molecules through the deposited film, limiting the effects on the crystal structure stabilization. Our results also show that the phase stabilization with molecules that migrate is long-lasting and resistant to moist air. These findings enable reliable formation and processing of α-FAPbI3 films via vapor deposition.- Published
- 2024
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10. Synergistic Role of Water and Oxygen Leads to Degradation in Formamidinium-Based Halide Perovskites.
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Hidalgo J, Kaiser W, An Y, Li R, Oh Z, Castro-Méndez AF, LaFollette DK, Kim S, Lai B, Breternitz J, Schorr S, Perini CAR, Mosconi E, De Angelis F, and Correa-Baena JP
- Abstract
Mixed-cation metal halide perovskites have shown remarkable progress in photovoltaic applications with high power conversion efficiencies. However, to achieve large-scale deployment of this technology, efficiencies must be complemented by long-term durability. The latter is limited by external factors, such as exposure to humidity and air, which lead to the rapid degradation of the perovskite materials and devices. In this work, we study the mechanisms causing Cs and formamidinium (FA)-based halide perovskite phase transformations and stabilization during moisture and air exposure. We use in situ X-ray scattering, X-ray photoelectron spectroscopy, and first-principles calculations to study these chemical interactions and their effects on structure. We unravel a surface reaction pathway involving the dissolution of FAI by water and iodide oxidation by oxygen, driving the Cs/FA ratio into thermodynamically unstable regions, leading to undesirable phase transformations. This work demonstrates the interplay of bulk phase transformations with surface chemical reactions, providing a detailed understanding of the degradation mechanism and strategies for designing durable and efficient perovskite materials.
- Published
- 2023
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11. Resolving Nonlinear Recombination Dynamics in Semiconductors via Ultrafast Excitation Correlation Spectroscopy: Photoluminescence versus Photocurrent Detection.
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Rojas-Gatjens E, Yallum KM, Shi Y, Zheng Y, Bills T, Perini CAR, Correa-Baena JP, Ginger DS, Banerji N, and Silva-Acuña C
- Abstract
We explore the application of excitation correlation spectroscopy to detect nonlinear photophysical dynamics in two distinct semiconductor classes through time-integrated photoluminescence and photocurrent measurements. In this experiment, two variably delayed femtosecond pulses excite the semiconductor, and the time-integrated photoluminescence or photocurrent component arising from the nonlinear dynamics of the populations induced by each pulse is measured as a function of inter-pulse delay by phase-sensitive detection with a lock-in amplifier. We focus on two limiting materials systems with contrasting optical properties: a prototypical lead-halide perovskite (LHP) solar cell, in which primary photoexcitations are charge photocarriers, and a single-component organic-semiconductor diode, which features Frenkel excitons as primary photoexcitations. The photoexcitation dynamics perceived by the two detection schemes in these contrasting systems are distinct. Nonlinear-dynamic contributions in the photoluminescence detection scheme arise from contributions to radiative recombination in both materials systems, while photocurrent arises directly in the LHP but indirectly following exciton dissociation in the organic system. Consequently, the basic photophysics of the two systems are reflected differently when comparing measurements with the two detection schemes. Our results indicate that photoluminescence detection in the LHP system provides valuable information about trap-assisted and Auger recombination processes, but that these processes are convoluted in a nontrivial way in the photocurrent response and are therefore difficult to differentiate. In contrast, the organic-semiconductor system exhibits more directly correlated responses in the nonlinear photoluminescence and photocurrent measurements, as charge carriers are secondary excitations only generated through exciton dissociation processes. We propose that bimolecular annihilation pathways mainly contribute to the generation of charge carriers in single-component organic semiconductor devices. Overall, our work highlights the utility of excitation correlation spectroscopy in modern semiconductor materials research, particularly in the analysis of nonlinear photophysical processes, which are deterministic for their electronic and optical properties., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)
- Published
- 2023
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12. Solvent and A-Site Cation Control Preferred Crystallographic Orientation in Bromine-Based Perovskite Thin Films.
- Author
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Hidalgo J, An Y, Yehorova D, Li R, Breternitz J, Perini CAR, Hoell A, Boix PP, Schorr S, Kretchmer JS, and Correa-Baena JP
- Abstract
Preferred crystallographic orientation in polycrystalline films is desirable for efficient charge carrier transport in metal halide perovskites and semiconductors. However, the mechanisms that determine the preferred orientation of halide perovskites are still not well understood. In this work, we investigate crystallographic orientation in lead bromide perovskites. We show that the solvent of the precursor solution and organic A-site cation strongly affect the preferred orientation of the deposited perovskite thin films. Specifically, we show that the solvent, dimethylsulfoxide, influences the early stages of crystallization and induces preferred orientation in the deposited films by preventing colloidal particle interactions. Additionally, the methylammonium A-site cation induces a higher degree of preferred orientation than the formamidinium counterpart. We use density functional theory to show that the lower surface energy of the (100) plane facets in methylammonium-based perovskites, compared to the (110) planes, is the reason for the higher degree of preferred orientation. In contrast, the surface energy of the (100) and (110) facets is similar for formamidinium-based perovskites, leading to lower degree of preferred orientation. Furthermore, we show that different A-site cations do not significantly affect ion diffusion in bromine-based perovskite solar cells but impact ion density and accumulation, leading to increased hysteresis. Our work highlights the interplay between the solvent and organic A-site cation which determine crystallographic orientation and plays a critical role in the electronic properties and ionic migration of solar cells., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)
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- 2023
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13. Machine Learning Enables Prediction of Halide Perovskites' Optical Behavior with >90% Accuracy.
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Srivastava M, Hering AR, An Y, Correa-Baena JP, and Leite MS
- Abstract
The composition-dependent degradation of hybrid organic-inorganic perovskites (HOIPs) due to environmental stressors still precludes their commercialization. It is very difficult to quantify their behavior upon exposure to each stressor by exclusively using trial-and-error methods due to the high-dimensional parameter space involved. We implement machine learning (ML) models using high-throughput, in situ photoluminescence (PL) to predict the response of Cs
y FA1- y Pb(Brx I1- x )3 while exposed to relative humidity cycles. We quantitatively compare three ML models while generating forecasts of environment-dependent PL responses: linear regression, echo state network, and seasonal autoregressive integrated moving average with exogenous regressor algorithms. We achieve accuracy of >90% for the latter, while tracking PL changes over a 50 h window. Samples with 17% of Cs content consistently showed a PL increase as a function of cycle. Our precise time-series forecasts can be extended to other HOIP families, illustrating the potential of data-centric approaches to accelerate material development for clean-energy devices., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)- Published
- 2023
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14. Interface Reconstruction from Ruddlesden-Popper Structures Impacts Stability in Lead Halide Perovskite Solar Cells.
- Author
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Perini CAR, Rojas-Gatjens E, Ravello M, Castro-Mendez AF, Hidalgo J, An Y, Kim S, Lai B, Li R, Silva-Acuña C, and Correa-Baena JP
- Abstract
The impact of the bulky-cation-modified interfaces on halide perovskite solar cell stability is underexplored. In this work, the thermal instability of the bulky-cation interface layers used in the state-of-the-art solar cells is demonstrated. X-ray photoelectron spectroscopy and synchrotron-based grazing-incidence X-ray scattering measurements reveal significant changes in the chemical composition and structure at the surface of these films that occur under thermal stress. The changes impact charge-carrier dynamics and device operation, as shown in transient photoluminescence, excitation correlation spectroscopy, and solar cells. The type of cation used for surface treatment affects the extent of these changes, where long carbon chains provide more stable interfaces. These results highlight that prolonged annealing of the treated interfaces is critical to enable reliable reporting of performances and to drive the selection of different bulky cations., (© 2022 Wiley-VCH GmbH.)
- Published
- 2022
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15. Formation of a Secondary Phase in Thermally Evaporated MAPbI 3 and Its Effects on Solar Cell Performance.
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Castro-Méndez AF, Perini CAR, Hidalgo J, Ranke D, Vagott JN, An Y, Lai B, Luo Y, Li R, and Correa-Baena JP
- Abstract
Thermal evaporation is a promising deposition technique to scale up perovskite solar cells (PSCs) to large areas, but the lack of understanding of the mechanisms that lead to high-quality evaporated methylammonium lead triiodide (MAPbI
3 ) films gives rise to devices with efficiencies lower than those obtained by spin coating. This work investigates the crystalline properties of MAPbI3 deposited by the thermal coevaporation of PbI2 and MAI, where the MAI evaporation rate is controlled by setting different temperatures for the MAI source and the PbI2 deposition rate is controlled with a quartz crystal microbalance (QCM). Using grazing incident wide-angle X-ray scattering (GIWAXS) and X-ray diffraction (XRD), we identify the formation of a secondary orthorhombic phase (with a Pnma space group) that appears at MAI source temperatures below 155 °C. With synchrotron-based X-ray fluorescence (XRF) microscopy, we show that the changes in crystalline phases are not necessarily due to changes in stoichiometry. The films show a stochiometric composition when the MAI source is heated between 140 to 155 °C, and the samples become slightly MAI rich at 165 °C. Increasing the MAI temperature beyond 165 °C introduces an excess of MAI in the film, which promotes the formation of films with low crystallinity that contain low-dimensional perovskites. When they are incorporated in solar cells, the films deposited at 165 °C result in the champion power conversion efficiency, although the presence of a small amount of low-dimensional perovskite may lead to a lower open-circuit voltage. We hypothesize that the formation of secondary phases in evaporated films limits the performance of PSCs and that their formation can be suppressed by controlling the MAI source temperature, bringing the film toward a phase-pure tetragonal structure. Control of the phases during perovskite evaporation is therefore crucial to obtain high-performance solar cells.- Published
- 2022
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16. Efficient perovskite solar cells via improved carrier management.
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Yoo JJ, Seo G, Chua MR, Park TG, Lu Y, Rotermund F, Kim YK, Moon CS, Jeon NJ, Correa-Baena JP, Bulović V, Shin SS, Bawendi MG, and Seo J
- Abstract
Metal halide perovskite solar cells (PSCs) are an emerging photovoltaic technology with the potential to disrupt the mature silicon solar cell market. Great improvements in device performance over the past few years, thanks to the development of fabrication protocols
1-3 , chemical compositions4,5 and phase stabilization methods6-10 , have made PSCs one of the most efficient and low-cost solution-processable photovoltaic technologies. However, the light-harvesting performance of these devices is still limited by excessive charge carrier recombination. Despite much effort, the performance of the best-performing PSCs is capped by relatively low fill factors and high open-circuit voltage deficits (the radiative open-circuit voltage limit minus the high open-circuit voltage)11 . Improvements in charge carrier management, which is closely tied to the fill factor and the open-circuit voltage, thus provide a path towards increasing the device performance of PSCs, and reaching their theoretical efficiency limit12 . Here we report a holistic approach to improving the performance of PSCs through enhanced charge carrier management. First, we develop an electron transport layer with an ideal film coverage, thickness and composition by tuning the chemical bath deposition of tin dioxide (SnO2 ). Second, we decouple the passivation strategy between the bulk and the interface, leading to improved properties, while minimizing the bandgap penalty. In forward bias, our devices exhibit an electroluminescence external quantum efficiency of up to 17.2 per cent and an electroluminescence energy conversion efficiency of up to 21.6 per cent. As solar cells, they achieve a certified power conversion efficiency of 25.2 per cent, corresponding to 80.5 per cent of the thermodynamic limit of its bandgap.- Published
- 2021
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17. Protecting hot carriers by tuning hybrid perovskite structures with alkali cations.
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Wang T, Jin L, Hidalgo J, Chu W, Snaider JM, Deng S, Zhu T, Lai B, Prezhdo O, Correa-Baena JP, and Huang L
- Abstract
Successful implementation of hot carrier solar cells requires preserving high carrier temperature as carriers migrate through the active layer. Here, we demonstrated that addition of alkali cations in hybrid organic-inorganic lead halide perovskites led to substantially elevated carrier temperature, reduced threshold for phonon bottleneck, and enhanced hot carrier transport. The synergetic effects from the Rb, Cs, and K cations result in ~900 K increase in the effective carrier temperature at a carrier density around 10
18 cm-3 with an excitation 1.45 eV above the bandgap. In the doped thin films, the protected hot carriers migrate 100 s of nanometers longer than the undoped sample as imaged by ultrafast microscopy. We attributed these improvements to the relaxation of lattice strain and passivation of halide vacancies by alkali cations based on x-ray structural characterizations and first principles calculations., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)- Published
- 2020
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18. Snapshots of Life-Early Career Materials Scientists Managing in the Midst of a Pandemic.
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Bao Y, Bossion A, Brambilla D, Buriak JM, Cai K, Chen L, Cooley JA, Correa-Baena JP, Dagdelen JM, Fenniri MZ, Horton MK, Joshi H, Khau BV, Kupgan G, La Pierre HS, Rao C, Rosales AM, Wang D, and Yan Q
- Published
- 2020
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19. The Doping Mechanism of Halide Perovskite Unveiled by Alkaline Earth Metals.
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Phung N, Félix R, Meggiolaro D, Al-Ashouri A, Sousa E Silva G, Hartmann C, Hidalgo J, Köbler H, Mosconi E, Lai B, Gunder R, Li M, Wang KL, Wang ZK, Nie K, Handick E, Wilks RG, Marquez JA, Rech B, Unold T, Correa-Baena JP, Albrecht S, De Angelis F, Bär M, and Abate A
- Abstract
Halide perovskites are a strong candidate for the next generation of photovoltaics. Chemical doping of halide perovskites is an established strategy to prepare the highest efficiency and most stable perovskite-based solar cells. In this study, we unveil the doping mechanism of halide perovskites using a series of alkaline earth metals. We find that low doping levels enable the incorporation of the dopant within the perovskite lattice, whereas high doping concentrations induce surface segregation. The threshold from low to high doping regime correlates to the size of the doping element. We show that the low doping regime results in a more n-type material, while the high doping regime induces a less n-type doping character. Our work provides a comprehensive picture of the unique doping mechanism of halide perovskites, which differs from classical semiconductors. We proved the effectiveness of the low doping regime for the first time, demonstrating highly efficient methylammonium lead iodide based solar cells in both n-i-p and p-i-n architectures.
- Published
- 2020
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20. Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites.
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Correa-Baena JP, Luo Y, Brenner TM, Snaider J, Sun S, Li X, Jensen MA, Hartono NTP, Nienhaus L, Wieghold S, Poindexter JR, Wang S, Meng YS, Wang T, Lai B, Holt MV, Cai Z, Bawendi MG, Huang L, Buonassisi T, and Fenning DP
- Abstract
The role of the alkali metal cations in halide perovskite solar cells is not well understood. Using synchrotron-based nano-x-ray fluorescence and complementary measurements, we found that the halide distribution becomes homogenized upon addition of cesium iodide, either alone or with rubidium iodide, for substoichiometric, stoichiometric, and overstoichiometric preparations, where the lead halide is varied with respect to organic halide precursors. Halide homogenization coincides with long-lived charge carrier decays, spatially homogeneous carrier dynamics (as visualized by ultrafast microscopy), and improved photovoltaic device performance. We found that rubidium and potassium phase-segregate in highly concentrated clusters. Alkali metals are beneficial at low concentrations, where they homogenize the halide distribution, but at higher concentrations, they form recombination-active second-phase clusters., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2019
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21. Planar Perovskite Solar Cells with High Open-Circuit Voltage Containing a Supramolecular Iron Complex as Hole Transport Material Dopant.
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Saygili Y, Turren-Cruz SH, Olthof S, Saes BWH, Pehlivan IB, Saliba M, Meerholz K, Edvinsson T, Zakeeruddin SM, Grätzel M, Correa-Baena JP, Hagfeldt A, Freitag M, and Tress W
- Abstract
In perovskite solar cells (PSCs), the most commonly used hole transport material (HTM) is spiro-OMeTAD, which is typically doped by metalorganic complexes, for example, based on Co, to improve charge transport properties and thereby enhance the photovoltaic performance of the device. In this study, we report a new hemicage-structured iron complex, 1,3,5-tris(5'-methyl-2,2'-bipyridin-5-yl)ethylbenzene Fe(III)-tris(bis(trifluoromethylsulfonyl)imide), as a p-type dopant for spiro-OMeTAD. The formal redox potential of this compound was measured as 1.29 V vs. the standard hydrogen electrode, which is slightly (20 mV) more positive than that of the commercial cobalt dopant FK209. Photoelectron spectroscopy measurements confirm that the iron complex acts as an efficient p-dopant, as evidenced in an increase of the spiro-OMeTAD work function. When fabricating planar PSCs with the HTM spiro-OMeTAD doped by 5 mol % of the iron complex, a power conversion efficiency of 19.5 % (AM 1.5G, 100 mW cm
-2 ) is achieved, compared to 19.3 % for reference devices with FK209. Open circuit voltages exceeding 1.2 V at 1 sun and reaching 1.27 V at 3 suns indicate that recombination at the perovskite/HTM interface is low when employing this iron complex. This work contributes to recent endeavors to reduce recombination losses in perovskite solar cells., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
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22. Perovskite Solar Cells: From the Laboratory to the Assembly Line.
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Abate A, Correa-Baena JP, Saliba M, Su'ait MS, and Bella F
- Abstract
Despite the fact that perovskite solar cells (PSCs) have a strong potential as a next-generation photovoltaic technology due to continuous efficiency improvements and the tunable properties, some important obstacles remain before industrialization is feasible. For example, the selection of low-cost or easy-to-prepare materials is essential for back-contacts and hole-transporting layers. Likewise, the choice of conductive substrates, the identification of large-scale manufacturing techniques as well as the development of appropriate aging protocols are key objectives currently under investigation by the international scientific community. This Review analyses the above aspects and highlights the critical points that currently limit the industrial production of PSCs and what strategies are emerging to make these solar cells the leaders in the photovoltaic field., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2018
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23. Perovskite Solar Cells: From the Atomic Level to Film Quality and Device Performance.
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Saliba M, Correa-Baena JP, Grätzel M, Hagfeldt A, and Abate A
- Abstract
Organic-inorganic perovskites have made tremendous progress in recent years due to exceptional material properties such as high panchromatic absorption, charge carrier diffusion lengths, and a sharp optical band edge. The combination of high-quality semiconductor performance with low-cost deposition techniques seems to be a match made in heaven, creating great excitement far beyond academic ivory towers. This is particularly true for perovskite solar cells (PSCs) that have shown unprecedented gains in efficiency and stability over a time span of just five years. Now there are serious efforts for commercialization with the hope that PSCs can make a major impact in generating inexpensive, sustainable solar electricity. In this Review, we will focus on perovskite material properties as well as on devices from the atomic to the thin film level to highlight the remaining challenges and to anticipate the future developments of PSCs., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2018
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24. Promises and challenges of perovskite solar cells.
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Correa-Baena JP, Saliba M, Buonassisi T, Grätzel M, Abate A, Tress W, and Hagfeldt A
- Abstract
The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years' time. At this stage of their development, the key issues concern how to achieve further improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms., (Copyright © 2017, American Association for the Advancement of Science.)
- Published
- 2017
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25. Globularity-Selected Large Molecules for a New Generation of Multication Perovskites.
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Gholipour S, Ali AM, Correa-Baena JP, Turren-Cruz SH, Tajabadi F, Tress W, Taghavinia N, Grätzel M, Abate A, De Angelis F, Gaggioli CA, Mosconi E, Hagfeldt A, and Saliba M
- Abstract
Perovskite solar cells (PSCs) use perovskites with an APbX
3 structure, where A is a monovalent cation and X is a halide such as Cl, Br, and/or I. Currently, the cations for high-efficiency PSCs are Rb, Cs, methylammonium (MA), and/or formamidinium (FA). Molecules larger than FA, such as ethylammonium (EA), guanidinium (GA), and imidazolium (IA), are usually incompatible with photoactive "black"-phase perovskites. Here, novel molecular descriptors for larger molecular cations are introduced using a "globularity factor", i.e., the discrepancy of the molecular shape and an ideal sphere. These cationic radii differ significantly from previous reports, showing that especially ethylammonium (EA) is only slightly larger than FA. This makes EA a suitable candidate for multication 3D perovskites that have potential for unexpected and beneficial properties (suppressing halide segregation, stability). This approach is tested experimentally showing that surprisingly large quantities of EA get incorporated, in contrast to most previous reports where only small quantities of larger molecular cations can be tolerated as "additives". MA/EA perovskites are characterized experimentally with a band gap ranging from 1.59 to 2.78 eV, demonstrating some of the most blue-shifted PSCs reported to date. Furthermore, one of the compositions, MA0.5 EA0.5 PbBr3 , shows an open circuit voltage of 1.58 V, which is the highest to date with a conventional PSC architecture., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2017
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26. Improving the Carrier Lifetime of Tin Sulfide via Prediction and Mitigation of Harmful Point Defects.
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Polizzotti A, Faghaninia A, Poindexter JR, Nienhaus L, Steinmann V, Hoye RLZ, Felten A, Deyine A, Mangan NM, Correa-Baena JP, Shin SS, Jaffer S, Bawendi MG, Lo C, and Buonassisi T
- Abstract
Tin monosulfide (SnS) is an emerging thin-film absorber material for photovoltaics. An outstanding challenge is to improve carrier lifetimes to >1 ns, which should enable >10% device efficiencies. However, reported results to date have only demonstrated lifetimes at or below 100 ps. In this study, we employ defect modeling to identify the sulfur vacancy and defects from Fe, Co, and Mo as most recombination-active. We attempt to minimize these defects in crystalline samples through high-purity, sulfur-rich growth and experimentally improve lifetimes to >3 ns, thus achieving our 1 ns goal. This framework may prove effective for unlocking the lifetime potential in other emerging thin-film materials by rapidly identifying and mitigating lifetime-limiting point defects.
- Published
- 2017
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27. High Tolerance to Iron Contamination in Lead Halide Perovskite Solar Cells.
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Poindexter JR, Hoye RLZ, Nienhaus L, Kurchin RC, Morishige AE, Looney EE, Osherov A, Correa-Baena JP, Lai B, Bulović V, Stevanović V, Bawendi MG, and Buonassisi T
- Abstract
The relationship between charge-carrier lifetime and the tolerance of lead halide perovskite (LHP) solar cells to intrinsic point defects has drawn much attention by helping to explain rapid improvements in device efficiencies. However, little is known about how charge-carrier lifetime and solar cell performance in LHPs are affected by extrinsic defects (i.e., impurities), including those that are common in manufacturing environments and known to introduce deep levels in other semiconductors. Here, we evaluate the tolerance of LHP solar cells to iron introduced via intentional contamination of the feedstock and examine the root causes of the resulting efficiency losses. We find that comparable efficiency losses occur in LHPs at feedstock iron concentrations approximately 100 times higher than those in p-type silicon devices. Photoluminescence measurements correlate iron concentration with nonradiative recombination, which we attribute to the presence of deep-level iron interstitials, as calculated from first-principles, as well as iron-rich particles detected by synchrotron-based X-ray fluorescence microscopy. At moderate contamination levels, we witness prominent recovery of device efficiencies to near-baseline values after biasing at 1.4 V for 60 s in the dark. We theorize that this temporary effect arises from improved charge-carrier collection enhanced by electric fields strengthened from ion migration toward interfaces. Our results demonstrate that extrinsic defect tolerance contributes to high efficiencies in LHP solar cells, which inspires further investigation into potential large-scale manufacturing cost savings as well as the degree of overlap between intrinsic and extrinsic defect tolerance in LHPs and "perovskite-inspired" lead-free stable alternatives.
- Published
- 2017
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28. High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact.
- Author
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Aitola K, Domanski K, Correa-Baena JP, Sveinbjörnsson K, Saliba M, Abate A, Grätzel M, Kauppinen E, Johansson EMJ, Tress W, Hagfeldt A, and Boschloo G
- Abstract
Mixed ion perovskite solar cells (PSC) are manufactured with a metal-free hole contact based on press-transferred single-walled carbon nanotube (SWCNT) film infiltrated with 2,2,7,-7-tetrakis(N,N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD). By means of maximum power point tracking, their stabilities are compared with those of standard PSCs employing spin-coated Spiro-OMeTAD and a thermally evaporated Au back contact, under full 1 sun illumination, at 60 °C, and in a N
2 atmosphere. During the 140 h experiment, the solar cells with the Au electrode experience a dramatic, irreversible efficiency loss, rendering them effectively nonoperational, whereas the SWCNT-contacted devices show only a small linear efficiency loss with an extrapolated lifetime of 580 h., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2017
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29. Improving efficiency and stability of perovskite solar cells with photocurable fluoropolymers.
- Author
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Bella F, Griffini G, Correa-Baena JP, Saracco G, Grätzel M, Hagfeldt A, Turri S, and Gerbaldi C
- Abstract
Organometal halide perovskite solar cells have demonstrated high conversion efficiency but poor long-term stability against ultraviolet irradiation and water. We show that rapid light-induced free-radical polymerization at ambient temperature produces multifunctional fluorinated photopolymer coatings that confer luminescent and easy-cleaning features on the front side of the devices, while concurrently forming a strongly hydrophobic barrier toward environmental moisture on the back contact side. The luminescent photopolymers re-emit ultraviolet light in the visible range, boosting perovskite solar cells efficiency to nearly 19% under standard illumination. Coated devices reproducibly retain their full functional performance during prolonged operation, even after a series of severe aging tests carried out for more than 6 months., (Copyright © 2016, American Association for the Advancement of Science.)
- Published
- 2016
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30. Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance.
- Author
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Saliba M, Matsui T, Domanski K, Seo JY, Ummadisingu A, Zakeeruddin SM, Correa-Baena JP, Tress WR, Abate A, Hagfeldt A, and Grätzel M
- Abstract
All of the cations currently used in perovskite solar cells abide by the tolerance factor for incorporation into the lattice. We show that the small and oxidation-stable rubidium cation (Rb
+ ) can be embedded into a "cation cascade" to create perovskite materials with excellent material properties. We achieved stabilized efficiencies of up to 21.6% (average value, 20.2%) on small areas (and a stabilized 19.0% on a cell 0.5 square centimeters in area) as well as an electroluminescence of 3.8%. The open-circuit voltage of 1.24 volts at a band gap of 1.63 electron volts leads to a loss in potential of 0.39 volts, versus 0.4 volts for commercial silicon cells. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full illumination and maximum power point tracking., (Copyright © 2016, American Association for the Advancement of Science.)- Published
- 2016
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31. Enhancing Efficiency of Perovskite Solar Cells via N-doped Graphene: Crystal Modification and Surface Passivation.
- Author
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Hadadian M, Correa-Baena JP, Goharshadi EK, Ummadisingu A, Seo JY, Luo J, Gholipour S, Zakeeruddin SM, Saliba M, Abate A, Grätzel M, and Hagfeldt A
- Abstract
Controlling the morphology and surface passivation in perovskite solar cells is paramount in obtaining optimal optoelectronic properties. This study incorporates N-doped graphene nanosheets in the perovskite layer, which simultaneously induces an improved morphology and surface passivation at the perovskite/spiro interface, resulting in enhancement in all photovoltaic parameters., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2016
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32. Additive-Free Transparent Triarylamine-Based Polymeric Hole-Transport Materials for Stable Perovskite Solar Cells.
- Author
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Matsui T, Petrikyte I, Malinauskas T, Domanski K, Daskeviciene M, Steponaitis M, Gratia P, Tress W, Correa-Baena JP, Abate A, Hagfeldt A, Grätzel M, Nazeeruddin MK, Getautis V, and Saliba M
- Subjects
- Drug Stability, Temperature, Amines chemistry, Calcium Compounds chemistry, Electric Power Supplies, Oxides chemistry, Polymers chemistry, Solar Energy, Titanium chemistry
- Abstract
Triarylamine-based polymers with different functional groups were synthetized as hole-transport materials (HTMs) for perovskite solar cells (PSCs). The novel materials enabled efficient PSCs without the use of chemical doping (or additives) to enhance charge transport. Devices employing poly(triarylamine) with methylphenylethenyl functional groups (V873) showed a power conversion efficiency of 12.3 %, whereas widely used additive-free poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) demonstrated 10.8 %. Notably, devices with V873 enabled stable PSCs under 1 sun illumination at maximum power point tracking for approximately 40 h at room temperature, and in the dark under elevated temperature (85 °C) for more than 140 h. This is in stark contrast to additive-containing devices, which degrade significantly within the same time frame. The results present remarkable progress towards stable PSC under real working conditions and industrial stress tests., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2016
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33. Unreacted PbI2 as a Double-Edged Sword for Enhancing the Performance of Perovskite Solar Cells.
- Author
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Jacobsson TJ, Correa-Baena JP, Halvani Anaraki E, Philippe B, Stranks SD, Bouduban ME, Tress W, Schenk K, Teuscher J, Moser JE, Rensmo H, and Hagfeldt A
- Abstract
Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that not only the composition but also the precise stoichiometry is important for the device performance. Recent reports have, for example, demonstrated small amount of PbI2 in the perovskite films to be beneficial for the overall performance of both the standard perovskite, CH3NH3PbI3, as well as for the mixed perovskites (CH3NH3)x(CH(NH2)2)(1-x)PbBryI(3-y). In this work a broad range of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photo electron spectroscopy (PES), transient absorption spectroscopy (TAS), UV-vis, electroluminescence (EL), photoluminescence (PL), and confocal PL mapping have been used to further understand the importance of remnant PbI2 in perovskite solar cells. Our best devices were over 18% efficient, and had in line with previous results a small amount of excess PbI2. For the PbI2-deficient samples, the photocurrent dropped, which could be attributed to accumulation of organic species at the grain boundaries, low charge carrier mobility, and decreased electron injection into the TiO2. The PbI2-deficient compositions did, however, also have advantages. The record Voc was as high as 1.20 V and was found in PbI2-deficient samples. This was correlated with high crystal quality, longer charge carrier lifetimes, and high PL yields and was rationalized as a consequence of the dynamics of the perovskite formation. We further found the ion migration to be obstructed in the PbI2-deficient samples, which decreased the JV hysteresis and increased the photostability. PbI2-deficient synthesis conditions can thus be used to deposit perovskites with excellent crystal quality but with the downside of grain boundaries enriched in organic species, which act as a barrier toward current transport. Exploring ways to tune the synthesis conditions to give the high crystal quality obtained under PbI2-poor condition while maintaining the favorable grain boundary characteristics obtained under PbI2-rich conditions would thus be a strategy toward more efficiency devices.
- Published
- 2016
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34. Optical analysis of CH 3 NH 3 Sn x Pb 1- x I 3 absorbers: a roadmap for perovskite-on-perovskite tandem solar cells.
- Author
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Anaya M, Correa-Baena JP, Lozano G, Saliba M, Anguita P, Roose B, Abate A, Steiner U, Grätzel M, Calvo ME, Hagfeldt A, and Míguez H
- Abstract
Organic-inorganic perovskite structures in which lead is substituted by tin are exceptional candidates for broadband light absorption. Herein we present a thorough analysis of the optical properties of CH
3 NH3 Snx Pb1- x I3 films, providing the field with definitive insights about the possibilities of these materials for perovskite solar cells of superior efficiency. We report a user's guide based on the first set of optical constants obtained for a series of tin/lead perovskite films, which was only possible to measure due to the preparation of optical quality thin layers. According to the Shockley-Queisser theory, CH3 NH3 Snx Pb1- x I3 compounds promise a substantial enhancement of both short circuit photocurrent and power conversion efficiency in single junction solar cells. Moreover, we propose a novel tandem architecture design in which both top and bottom cells are made of perovskite absorbers. Our calculations indicate that such perovskite-on-perovskite tandem devices could reach efficiencies over 35%. Our analysis serves to establish the first roadmap for this type of cells based on actual optical characterization data. We foresee that this study will encourage the research on novel near-infrared perovskite materials for photovoltaic applications, which may have implications in the rapidly emerging field of tandem devices.- Published
- 2016
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35. Unbroken Perovskite: Interplay of Morphology, Electro-optical Properties, and Ionic Movement.
- Author
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Correa-Baena JP, Anaya M, Lozano G, Tress W, Domanski K, Saliba M, Matsui T, Jacobsson TJ, Calvo ME, Abate A, Grätzel M, Míguez H, and Hagfeldt A
- Abstract
Hybrid organic-inorganic perovskite materials have risen up as leading components for light-harvesting applications. However, to date many questions are still open concerning the operation of perovskite solar cells (PSCs). A systematic analysis of the interplay among structural features, optoelectronic performance, and ionic movement behavior for FA0.83 MA0.17 Pb(I0.83 Br0.17 )3 PSCs is presented, which yield high power conversion efficiencies up to 20.8%., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2016
- Full Text
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36. Not All That Glitters Is Gold: Metal-Migration-Induced Degradation in Perovskite Solar Cells.
- Author
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Domanski K, Correa-Baena JP, Mine N, Nazeeruddin MK, Abate A, Saliba M, Tress W, Hagfeldt A, and Grätzel M
- Abstract
Perovskite solar cells (PSCs) have now achieved efficiencies in excess of 22%, but very little is known about their long-term stability under thermal stress. So far, stability reports have hinted at the importance of substituting the organic components, but little attention has been given to the metal contact. We investigated the stability of state-of-the-art PSCs with efficiencies exceeding 20%. Remarkably, we found that exposing PSCs to a temperature of 70 °C is enough to induce gold migration through the hole-transporting layer (HTL), spiro-MeOTAD, and into the perovskite material, which in turn severely affects the device performance metrics under working conditions. Importantly, we found that the main cause of irreversible degradation is not due to decomposition of the organic and hybrid perovskite layers. By introducing a Cr metal interlayer between the HTL and gold electrode, high-temperature-induced irreversible long-term losses are avoided. This key finding is essential in the quest for achieving high efficiency, long-term stable PSCs which, in order to be commercially viable, need to withstand hard thermal stress tests.
- Published
- 2016
- Full Text
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37. Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency.
- Author
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Saliba M, Matsui T, Seo JY, Domanski K, Correa-Baena JP, Nazeeruddin MK, Zakeeruddin SM, Tress W, Abate A, Hagfeldt A, and Grätzel M
- Abstract
Today's best perovskite solar cells use a mixture of formamidinium and methylammonium as the monovalent cations. With the addition of inorganic cesium, the resulting triple cation perovskite compositions are thermally more stable, contain less phase impurities and are less sensitive to processing conditions. This enables more reproducible device performances to reach a stabilized power output of 21.1% and ∼18% after 250 hours under operational conditions. These properties are key for the industrialization of perovskite photovoltaics.
- Published
- 2016
- Full Text
- View/download PDF
38. Morphological Characterization of ALD and Doping Effects on Mesoporous SnO2 Aerogels by XPS and Quantitative SEM Image Analysis.
- Author
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Correa-Baena JP, Artyushkova K, Santoro C, Atanassov P, and Agrios AG
- Abstract
Atomic layer deposition (ALD) is unsurpassed in its ability to create thin conformal coatings over very rough and/or porous materials. Yet although the coating thickness on flat surfaces can be measured by ellipsometry, characterization of these coatings on rough surfaces is difficult. Here, two techniques are demonstrated to provide such characterization of ALD-coated TiO2 over mesoporous SnO2 aerogel films on glass substrates, and insights are gained as to the ALD process. First, X-ray photoelectron spectroscopy (XPS) is used to determine the coating thickness over the aerogel, and the results (0.04 nm/cycle) agree well with ellipsometry on flat surfaces up to a coating thickness limit of about 6 nm. Second, quantitative analysis of SEM images of the aerogel cross section is used to determine porosity and roughness, from which coating thickness can be inferred. The analysis reveals increasing porosity from the aerogel/air interface to the aerogel/substrate interface, indicating a thicker ALD coating near the air side, which is consistent with tortuous diffusion through the pores limiting access of ALD precursors to deeper parts of the film. SEM-derived porosity is generally useful in a thin film because bulk methods like nitrogen physisorption or mercury porosimetry are impractical for use with thin-film samples. Therefore, in this study SEM was also used to characterize quantitatively the morphologogical changes in SnO2 aerogel thin films due to doping with Sb. This study can be used as a methodology to understand morphological changes in different types of porous and/or rough materials.
- Published
- 2016
- Full Text
- View/download PDF
39. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells.
- Author
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Giordano F, Abate A, Correa Baena JP, Saliba M, Matsui T, Im SH, Zakeeruddin SM, Nazeeruddin MK, Hagfeldt A, and Graetzel M
- Abstract
Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%).
- Published
- 2016
- Full Text
- View/download PDF
40. Efficient luminescent solar cells based on tailored mixed-cation perovskites.
- Author
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Bi D, Tress W, Dar MI, Gao P, Luo J, Renevier C, Schenk K, Abate A, Giordano F, Correa Baena JP, Decoppet JD, Zakeeruddin SM, Nazeeruddin MK, Grätzel M, and Hagfeldt A
- Subjects
- Amidines chemistry, Electric Power Supplies, Electrons, Luminescence, Solutions chemistry, Sunlight, X-Ray Diffraction methods, Calcium Compounds chemistry, Cations chemistry, Oxides chemistry, Solar Energy, Titanium chemistry
- Abstract
We report on a new metal halide perovskite photovoltaic cell that exhibits both very high solar-to-electric power-conversion efficiency and intense electroluminescence. We produce the perovskite films in a single step from a solution containing a mixture of FAI, PbI2, MABr, and PbBr2 (where FA stands for formamidinium cations and MA stands for methylammonium cations). Using mesoporous TiO2 and Spiro-OMeTAD as electron- and hole-specific contacts, respectively, we fabricate perovskite solar cells that achieve a maximum power-conversion efficiency of 20.8% for a PbI2/FAI molar ratio of 1.05 in the precursor solution. Rietveld analysis of x-ray diffraction data reveals that the excess PbI2 content incorporated into such a film is about 3 weight percent. Time-resolved photoluminescence decay measurements show that the small excess of PbI2 suppresses nonradiative charge carrier recombination. This in turn augments the external electroluminescence quantum efficiency to values of about 0.5%, a record for perovskite photovoltaics approaching that of the best silicon solar cells. Correspondingly, the open-circuit photovoltage reaches 1.18 V under AM 1.5 sunlight.
- Published
- 2016
- Full Text
- View/download PDF
41. Transparent conducting aerogels of antimony-doped tin oxide.
- Author
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Correa Baena JP and Agrios AG
- Abstract
Bulk antimony-doped tin oxide aerogels are prepared by epoxide-initiated sol-gel processing. Tin and antimony precursors are dissolved in ethanol and water, respectively, and propylene oxide is added to cause rapid gelation of the sol, which is then dried supercritically. The Sb:Sn precursor mole ratio is varied from 0 to 30% to optimize the material conductivity and absorbance. The materials are characterized by electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), nitrogen physisorption analysis, a four-point probe resistivity measurement, and UV-vis diffuse reflectance spectroscopy. The samples possess morphology typical of aerogels without significant change with the amount of doping. Calcination at 450 °C produces a cassiterite crystal structure in all aerogel samples. Introduction of Sb at 15% in the precursor (7.6% Sb by XPS) yields a resistivity more than 3 orders of magnitude lower than an undoped SnO2 aerogel. Calcination at 800 °C reduces the resistivity by an additional 2 orders of magnitude to 30 Ω·cm, but results in a significant decrease in surface area and pore volume.
- Published
- 2014
- Full Text
- View/download PDF
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