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422 results on '"Grancini, Giulia"'

153. Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%.

Author

Cho, Kyung Teak, Trukhina, Olga, Roldán‐Carmona, Cristina, Ince, Mine, Gratia, Paul, Grancini, Giulia, Gao, Peng, Marszalek, Tomasz, Pisula, Wojciech, Reddy, Paidi Y., Torres, Tomás, and Nazeeruddin, Mohammad Khaja

Subjects
PHTHALOCYANINES, SOLAR energy conversion, ZINC phthalocyanine, PEROVSKITE, OPTOELECTRONICS
Abstract

Easily accessible tetra-5-hexylthiophene-, tetra-5-hexyl-2,2′-bisthiophene-substituted zinc phthalocyanines (ZnPcs) and tetra- tert-butyl ZnPc are employed as hole-transporting materials in mixed-ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.85Br0.15)3 solar cells, reaching the highest power conversion efficiency (PCE) so far for phthalocyanines. Results confirm that the photovoltaic performance is strongly influenced by both, the individual optoelectronic properties of ZnPcs and the aggregation of these tetrapyrrolic semiconductors in the solid thin film. The optimized devices exhibit PCE of 15.5% when using tetra-5-hexyl-2,2′-bisthiophene substituted ZnPcs, 13.3% for tetra- tert-butyl ZnPc, and a record 17.5% for tetra-5-hexylthiophene-based analogue under standard global 100 mW cm−2 AM 1.5G illumination. These results boost up the potential of solution-processed ZnPc derivatives as stable and economic hole-transport materials for large-scale applications, opening new frontiers toward a realistic, efficient, and inexpensive energy production. [ABSTRACT FROM AUTHOR]

Published
2017
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154. High-Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene-Rich, Hole-Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency.

Author

Zimmermann, Iwan, Urieta‐Mora, Javier, Gratia, Paul, Aragó, Juan, Grancini, Giulia, Molina‐Ontoria, Agustín, Ortí, Enrique, Martín, Nazario, and Nazeeruddin, Mohammad Khaja

Subjects
SOLAR cells, SMALL molecules, PHOTOVOLTAIC effect, ELECTROCHEMISTRY, PHOTOLUMINESCENCE, METHYLAMMONIUM
Abstract

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2- b:4,3- b′:5,6- b′′:8,7- b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs are tested in perovskite solar cells and power conversion efficiencies (PCE) of up to 18.1% under 1 sun irradiation are measured. This value is comparable with the 17.8% efficiency obtained using 2,2′,7,7′-tetrakis( N, N-di- p-methoxyphenylamine)-9,9′-spirobifluorene as a reference compound. Similarly, a significant quenching of the photoluminescence in the first nanosecond is observed, indicative of effective hole transfer. Additionally, the influence of introducing aliphatic alkyl chains acting as solubilizers on the device performance of the ATT molecules is investigated. Replacing the methoxy groups on the triarylamine sites by butoxy-, hexoxy-, or decoxy-substituents greatly improves the solubility of the compounds without changing the energy levels, yet at the same time significantly decreasing the conductivity as well as the PCE, 17.3% for ATT-OBu, 15.7% for ATT-OHex, and 9.7% for ATT-ODec. [ABSTRACT FROM AUTHOR]

Published
2017
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155. The Impact of the Crystallization Processes on the Structural and Optical Properties of Hybrid Perovskite Films for Photovoltaics

Author

Grancini, Giulia, primary, Marras, Sergio, additional, Prato, Mirko, additional, Giannini, Cinzia, additional, Quarti, Claudio, additional, De Angelis, Filippo, additional, De Bastiani, Michele, additional, Eperon, Giles E., additional, Snaith, Henry J., additional, Manna, Liberato, additional, and Petrozza, Annamaria, additional

Published
2014
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156. Molecular Packing and Electronic Processes in Amorphous-like Polymer Bulk Heterojunction Solar Cells with Fullerene Intercalation

Author

Xiao, Ting, primary, Xu, Haihua, additional, Grancini, Giulia, additional, Mai, Jiangquan, additional, Petrozza, Annamaria, additional, Jeng, U-Ser, additional, Wang, Yan, additional, Xin, Xin, additional, Lu, Yong, additional, Choon, Ng Siu, additional, Xiao, Hu, additional, Ong, Beng S., additional, Lu, Xinhui, additional, and Zhao, Ni, additional

Published
2014
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158. Excitons versus free charges in organo-lead tri-halide perovskites

Author

D’Innocenzo, Valerio, primary, Grancini, Giulia, additional, Alcocer, Marcelo J. P., additional, Kandada, Ajay Ram Srimath, additional, Stranks, Samuel D., additional, Lee, Michael M., additional, Lanzani, Guglielmo, additional, Snaith, Henry J., additional, and Petrozza, Annamaria, additional

Published
2014
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159. Three-Dimensional Self-Assembly of Networked Branched TiO2 Nanocrystal Scaffolds for Efficient Room-Temperature Processed Depleted Bulk Heterojunction Solar Cells

Author

Loiudice, Anna, primary, Grancini, Giulia, additional, Taurino, Antonietta, additional, Corricelli, Michela, additional, Belviso, Maria R., additional, Striccoli, Marinella, additional, Agostiano, Angela, additional, Curri, M. Lucia, additional, Petrozza, Annamaria, additional, Cozzoli, P. Davide, additional, Rizzo, Aurora, additional, and Gigli, Giuseppe, additional

Published
2014
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163. Charge Photogeneration in Donor–Acceptor Conjugated Materials: Influence of Excess Excitation Energy and Chain Length

Author

Tautz, Raphael, primary, Da Como, Enrico, additional, Wiebeler, Christian, additional, Soavi, Giancarlo, additional, Dumsch, Ines, additional, Fröhlich, Nils, additional, Grancini, Giulia, additional, Allard, Sybille, additional, Scherf, Ullrich, additional, Cerullo, Giulio, additional, Schumacher, Stefan, additional, and Feldmann, Jochen, additional

Published
2013
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167. Fabrication of flexible all-inorganic nanocrystal solar cells by room-temperature processing

Author

Loiudice, Anna, primary, Rizzo, Aurora, additional, Grancini, Giulia, additional, Biasiucci, Mariano, additional, Belviso, Maria R., additional, Corricelli, Michela, additional, Curri, M. Lucia, additional, Striccoli, Marinella, additional, Agostiano, Angela, additional, Cozzoli, P. Davide, additional, Petrozza, Annamaria, additional, Lanzani, Guglielmo, additional, and Gigli, Giuseppe, additional

Published
2013
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171. Ion Migration and the Role of Preconditioning Cycles in the Stabilization of the J- V Characteristics of Inverted Hybrid Perovskite Solar Cells.

Author

De Bastiani, Michele, Dell'Erba, Giorgio, Gandini, Marina, D'Innocenzo, Valerio, Neutzner, Stefanie, Kandada, Ajay Ram Srimath, Grancini, Giulia, Binda, Maddalena, Prato, Mirko, Ball, James M., Caironi, Mario, and Petrozza, Annamaria

Subjects
SOLAR cells, PEROVSKITE, ELECTRIC charge, DIRECT energy conversion, SOLAR energy
Abstract

Charge extracting layers play a key role in the elimination of hysteresis from J–V characteristics of inverted hybrid perovskite solar cells. Methanofullerene electron extracting layers stabilize short‐circuit photocurrents from the very first J–V scan, while preconditioning cycles are needed to stabilize the open‐circuit voltage owing to interaction between migrating iodide ions and the charge extraction layer. [ABSTRACT FROM AUTHOR]

Published
2016
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172. Ultrafast spectroscopic imaging of exfoliated graphene

Author

Grancini, Giulia, primary, Martino, Nicola, additional, Bianchi, Massimiliano, additional, Rizzi, Laura Giorgia, additional, Russo, Valeria, additional, Li Bassi, Andrea, additional, Casari, Carlo Spartaco, additional, Petrozza, Annamaria, additional, Sordan, Roman, additional, and Lanzani, Guglielmo, additional

Published
2012
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185. Effect of Crystallite Size on the Flexibility and Negative Compressibility of Hydrophobic Metal–Organic Frameworks

Author

Johnson, Liam J. W., Mirani, Diego, Le Donne, Andrea, Bartolomé, Luis, Amayuelas, Eder, López, Gabriel A., Grancini, Giulia, Carter, Marcus, Yakovenko, Andrey A., Trump, Benjamin A., Meloni, Simone, Zajdel, Paweł, and Grosu, Yaroslav

Abstract

Flexible nanoporous materials are of great interest for applications in many fields such as sensors, catalysis, material separation, and energy storage. Of these, metal–organic frameworks (MOFs) are the most explored thus far. However, tuning their flexibility for a particular application remains challenging. In this work, we explore the effect of the exogenousproperty of crystallite size on the flexibility of the ZIF-8 MOF. By subjecting hydrophobic ZIF-8 to hydrostatic compression with water, the flexibility of its empty framework and the giant negative compressibility it experiences during water intrusion were recorded via in operandosynchrotron irradiation. It was observed that as the crystallite size is reduced to the nanoscale, both flexibility and the negative compressibility of the framework are reduced by ∼25% and ∼15%, respectively. These results pave the way for exogenoustuning of flexibility in MOFs without altering their chemistries.

Published
2023
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186. Molecular Packing and Electronic Processes in Amorphous-like Polymer Bulk Heterojunction Solar Cells with Fullerene Intercalation.

Author

Ting Xiao, Haihua Xu, Grancini, Giulia, Jiangquan Mai, Petrozza, Annamaria, U-Ser Jeng, Yan Wang, Xin Xin, Yong Lu, Ng Siu Choon, Hu Xiao, Ong, Beng S., Xinhui Lu, and Ni Zhao

Subjects
POLYMERS, FULLERENES, PHOTOVOLTAIC cells, COPOLYMERS, X-ray scattering
Abstract

The interpenetrating morphology formed by the electron donor and acceptor materials is critical for the performance of polymer:fullerene bulk heterojunction (BHJ) photovoltaic (PV) cells. In this work we carried out a systematic investigation on a high PV efficiency (.6%) BHJ system consisting of a newly developed 5,6-difluorobenzo[c]1,2,5 thiadiazole-based copolymer, PFBT-T20TT, and a fullerene derivative. Grazing incidence X-ray scattering measurements reveal the lower-ordered nature of the BHJ system as well as an intermixing morphology with intercalation of fullerene molecules between the PFBT-T20TT lamella. Steady-state and transient photo-induced absorption spectroscopy reveal ultrafast charge transfer (CT) at the PFBT-T20TT/fullerene interface, indicating that the CT process is no longer limited by exciton diffusion. Furthermore, we extracted the hole mobility based on the space limited current (SCLC) model and found that more efficient hole transport is achieved in the PFBT-T20TT:fullerene BHJ as compared to pure PFBT-T20TT, showing a different trend as compared to the previously reported highly crystalline polymer:fullerene blend with a similar intercalation manner. Our study correlates the fullerene intercalated polymer lamella morphology with device performance and provides a coherent model to interpret the high photovoltaic performance of some of the recently developed weakly-ordered BHJ systems based on conjugated polymers with branched side-chain. [ABSTRACT FROM AUTHOR]

Published
2014
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188. Hyperbranched Quasi-1D TiO2Nanostructure for Hybrid Organic–Inorganic Solar Cells

Author

Ghadirzadeh, Ali, Passoni, Luca, Grancini, Giulia, Terraneo, Giancarlo, Li Bassi, Andrea, Petrozza, Annamaria, and Di Fonzo, Fabio

Abstract

The performance of hybrid solar cells is strongly affected by the device morphology. In this work, we demonstrate a poly(3-hexylthiophene-2,5-diyl)/TiO2hybrid solar cell where the TiO2photoanode comprises an array of tree-like hyperbranched quasi-1D nanostructures self-assembled from the gas phase. This advanced architecture enables us to increase the power conversion efficiency to over 1%, doubling the efficiency with respect to state of the art devices employing standard mesoporous titania photoanodes. This improvement is attributed to several peculiar features of this array of nanostructures: high interfacial area; increased optical density thanks to the enhanced light scattering; and enhanced crystallization of poly(3-hexylthiophene-2,5-diyl) inside the quasi-1D nanostructure.

Published
2015
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189. Ultrafast Energy Transfer in Ultrathin Organic Donor/Acceptor Blend.

Author

Srimath Kandada, Ajay Ram, Grancini, Giulia, Petrozza, Annamaria, Perissinotto, Stefano, Fazzi, Daniele, Raavi, Santosh Kumar, and Lanzani, Guglielmo

Subjects
*ENERGY transfer, *BUTYRIC acid, *SOLAR cells, *PHOTOVOLTAIC cells, *PHOTOEXCITATION
Abstract

It is common knowledge that poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend, a prototype system for bulk heterojunction (BHJ) solar cells, consists of a network of tens of nanometers-large donor-rich and acceptor-rich phases separated by extended finely intermixed border regions where PCBM diffuse into P3HT. Here we specifically address the photo-induced dynamics in a 10 nm thin P3HT/PCBM blend that consists of the intermixed region only. Using the multi-pass transient absorption technique (TrAMP) that enables us to perform ultra high sensitive measurements, we find that the primary process upon photoexcitation is ultrafast energy transfer from P3HT to PCBM. The expected charge separation due to hole transfer from PCBM to P3HT occurs in the 100 ps timescale. The derived picture is much different from the accepted view of ultra-fast electron transfer at the polymer/PCBM interface and provides new directions for the development of efficient devices. [ABSTRACT FROM AUTHOR]

Published
2013
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190. Three-Dimensional Self-Assembly of Networked Branched TiO2Nanocrystal Scaffolds for Efficient Room-Temperature Processed Depleted Bulk Heterojunction Solar Cells

Author

Loiudice, Anna, Grancini, Giulia, Taurino, Antonietta, Corricelli, Michela, Belviso, Maria R., Striccoli, Marinella, Agostiano, Angela, Curri, M. Lucia, Petrozza, Annamaria, Cozzoli, P. Davide, Rizzo, Aurora, and Gigli, Giuseppe

Abstract

In this work, we report on ∼4% power conversion efficiency (PCE) depleted bulk heterojunction (DBH) solar cells based on a high-quality electrode with a three-dimensional nanoscale architecture purposely designed so as to maximize light absorption and charge collection. The newly conceived architecture comprises a mesoporous electron-collecting film made of networked anisotropic metal-oxide nanostructures, which accommodates visible-to-infrared light harvesting quantum dots within the recessed regions of its volume. The three-dimensional electrodes were self-assembled by spin-coating a solution of colloidal branched anatase TiO2NCs (BNC), followed by photocatalytic removal of the native organic capping from their surface by a mild UV-light treatment and filling with small PbS NCs via infiltration. The PCE ∼ 4% of our TiO2BNC/PbS QD DBH solar cell features an enhancement of 84% over the performance obtained for a planar device fabricated under the same conditions. Overall, the DBH device fabrication procedure is entirely carried out under mild processing conditions at room temperature, thus holding promise for low-cost and large-scale manufacturing.

Published
2014
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191. Front Cover: Two‐Step Thermal Annealing: An Effective Route for 15 % Efficient Quasi‐2D Perovskite Solar Cells (ChemPlusChem 8/2021).

Author

Romano, Valentino, Najafi, Leyla, Sutanto, Albertus Adrian, Schileo, Giorgio, Queloz, Valentin, Bellani, Sebastiano, Prato, Mirko, Marras, Sergio, Nazeeruddin, Mohammad Khaja, D'Angelo, Giovanna, Bonaccorso, Francesco, and Grancini, Giulia

Subjects
SOLAR cells, PHOTOVOLTAIC power systems, PEROVSKITE, CHEMICAL formulas, CRYSTAL growth, THERMAL batteries
Abstract

Keywords: crystal growth; perovskites; solar cells; thermal annealing; thin films EN crystal growth perovskites solar cells thermal annealing thin films 1038 1038 1 09/01/21 20210801 NES 210801 B The Front Cover shows b the crystal structure of a Ruddlesden-Popper quasi-2D perovskite with chemical formula (PEA) SB 2 sb MA SB 39 sb Pb SB 40 sb I SB 121 sb (with PEA: phenylethylammonium and MA: methylammonium). Crystal growth, perovskites, solar cells, thermal annealing, thin films Front Cover: Two-Step Thermal Annealing: An Effective Route for 15 % Efficient Quasi-2D Perovskite Solar Cells (ChemPlusChem 8/2021). [Extracted from the article]

Published
2021
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192. Borderless collaboration is needed for COVID-19—A disease that knows no borders

Author

Mohamed, Kawthar, Rodríguez-Román, Eduardo, Rahmani, Farzaneh, Zhang, Hongbo, Ivanovska, Mariya, Makka, Sara A., Joya, Musa, Makuku, Rangarirai, Islam, Md Shahidul, Radwan, Nesrine, Rahmah, Laila, Goda, Rayan, Abarikwu, Sunny O., Shaw, Mujtaba, Zoghi, Samaneh, Irtsyan, Sevan, Ling, Irene, Cseprekal, Orsolya, Faten, Attig-Bahar, Hazar Sayar, Esra, Soloukey, Chagajeg, Grancini, Giulia, and Rezaei, Nima

Published
2020
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193. Lead‐Free Double Perovskites for Perovskite Solar Cells.

Author

Kung, Po-Kai, Li, Ming-Hsien, Lin, Pei-Ying, Jhang, Jia-Yun, Pantaler, Martina, Lupascu, Doru C., Grancini, Giulia, and Chen, Peter

Subjects
SOLAR cells, CHEMICAL stability, PRODUCTION sharing contracts (Oil & gas)
Abstract

Perovskite solar cells (PSCs) have achieved a high power conversion efficiency (PCE) with a credible certified value over 25%. More efforts have been devoted to the development of stable and ecofriendly perovskite materials. Lead‐free double perovskites (LFDPs) are a noteworthy choice as a photoactive layer because of their favorable photovoltaic (PV) properties, intrinsic chemical stability, and environmental friendliness. This Review presents various LFDP materials whose structural stability and optoelectronic properties are predicted by theoretical calculations. The synthesis and experimental properties of LFDPs and their applications in PSCs and optoelectronics in pursuing high performance, low toxicity, and functional stability are also reviewed. Perovskites active layers are critical for PSCs, and their appropriate properties are responsible for achieving a high PCE. On the other side, the stability of PSCs under working conditions is a critical requirement for their practical applications. Defect‐ordered perovskites are also presented to provide another outlook on lead‐free perovskite‐based PVs. The introduction and interest toward LFDP in PSCs can represent a viable solution to the toxicity issue, stimulate further research, and bring a real impact to future PV technologies. [ABSTRACT FROM AUTHOR]

Published
2020
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195. A Facile Preparative Route of Nanoscale Perovskites over Mesoporous Metal Oxide Films and Their Applications to Photosensitizers and Light Emitters

Author

Lee, Hyo Joong, Cho, Kyung Taek, Paek, Sanghyun, Lee, Yonghui, Huckaba, Aron Joel, Queloz, Valentin Ianis Emmanuel, Zimmermann, Iwan, Grancini, Giulia, Oveisi, Emad, Yoo, So-Min, Lee, Seul-Yi, Shin, Taeho, Kim, Myoung, and Nazeeruddin, Mohammad Khaja

Abstract

By two‐step sequential Pb2+ adsorption and reaction with methylammonium‐iodide (MAI) or ‐bromide (MABr) at a low concentration level of 0.06–0.10 m over mesoporous TiO2 or ZrO2 film, a well‐defined nanoscale CH3NH3PbI3 (MAPbI3) photosensitizer or CH3NH3PbBr3 (MAPbBr3) light emitter could be prepared in situ, respectively in a reproducible and atom‐economical way. The as‐prepared nanoscale perovskites are compared with their thin film counterparts in terms of light absorption/emission, crystallinity, surface morphology, and energy‐conversion efficiency. The nanoscale perovskite‐decorated films display more transparency than the bulky film due to the much lower amount deposited, while blueshifted and overwhelmingly brighter photoluminescence is observed in the “nano” relative to the “bulk” due to quantum size confinement. Transmission electron microscopy images also clearly show that a few nanometer‐sized perovskite dots are deposited homogeneously over the surface of TiO2‐ or ZrO2‐particulate film in the course of the current preparative route. When the nano‐MAPbI3 is tested as a photosensitizer in a solid‐state dye‐sensitized solar cell configuration with a very thin (≈650 nm) TiO2 mesoporous film, it has a promising initial power conversion efficiency of 6.23%, which outperformed the result of 2.28% from a typical organic molecular dye coded as MK‐2.

196. PbI2–HMPA Complex Pretreatment for Highly Reproducible and Efficient CH3NH3PbI3 Perovskite Solar Cells

Author

Zhang, Yi, Gao, Peng, Oveisi, Emad, Lee, Yonghui, Jeangros, Quentin, Grancini, Giulia, Paek, Sanghyun, Yaqing, Feng, and Nazeeruddin, Mohammad Khaja

Abstract

Interfacial engineering of the meso-TiO2 surface through a modified sequential deposition procedure involving a novel PbI2–HMPA complex pretreatment is conducted as a reproducible method for preparing MAPbI3 based perovskite solar cells providing the highest efficiencies yet reported with the polymer HTM layer. Grazing-incidence X-ray diffraction depth profiling confirms the formation of a perovskite film with a PbI2-rich region close to the electron transport layer (ETL) due to the strong interaction of HMPA with PbI2, which successfully retarded the dissolution of the PbI2 phase when depositing the perovskite layer on top. These results are further confirmed by energy-dispersive X-ray spectroscopy performed in a scanning transmission electron microscope, which reveals that the I/Pb ratio in samples treated with the complex is indeed reduced in the vicinity of the ETL contact when compared to samples without the treatment. The engineered interface leads to an average power conversion efficiency of 19.2% (reverse scan, standard deviation SD < 0.2) over 30 cells (best cell at 19.5% with high FF of 0.80).

197. Saddle-like, π-conjugated, cyclooctatetrathiophene-based, hole-transporting material for perovskite solar cells

Author

Urieta-Mora, Javier, García-Benito, Inés, Zimmermann, Iwan, Aragó, Juan, Calbo, Joaquín, Grancini, Giulia, Molina-Ontoria, Agustín, Ortí, Enrique, Martín, Nazario, and Nazeeruddin, Mohammad Khaja

Abstract

A flexible, saddle-like, π-conjugated skeleton composed of four fused thiophene rings forming a cyclooctatetrathiophene (CoTh) with four triphenylamines (CoTh-TTPA) is presented as a hole-transporting material (HTM) for perovskite solar cells. The new HTM shows a bright red color stemming from a direct conjugation between the TPA groups and the central CoTh scaffold. This results in a charge transfer band due to the combination of the weak acceptor moiety, the CoTh unit, and the electron-donating p-methoxytriphenylamine groups. CoTh-TTPA exhibits a suitable highest-occupied molecular orbital (HOMO) level in relation to the valence band edge of the perovskite, which ensures efficient hole extraction at the perovskite/HTM interface. It has been applied as the HTM in combination with a mixed perovskite ([FAPbI3]0.85[MAPbBr3]0.15) and a state-of-the-art triple cation perovskite ([(FAPbI3)0.87(MAPbBr3)0.13]0.92[CsPbI3]0.08) reaching noticeable light-to-energy conversion efficiencies of 16.3 and 15.9%, respectively. These values are slightly lower than those measured for the benchmark spiro-OMeTAD HTM. The HTM properties have been analyzed by means of photoluminescence and conductivity experiments, which demonstrated a better hole extraction and conductivity for spiro-OMeTAD.

198. Two-Step Thermal Annealing: An Effective Route for 15 % Efficient Quasi-2D Perovskite Solar Cells

Author

Romano, Valentino, Najafi, Leyla, Sutanto, Albertus Adrian, Schileo, Giorgio, Queloz, Valentin, Bellani, Sebastiano, Prato, Mirko, Marras, Sergio, Nazeeruddin, Mohammad Khaja, D'Angelo, Giovanna, Bonaccorso, Francesco, and Grancini, Giulia

Subjects
thermal annealing, thin films, crystal growth, solar cells, perovskites
Abstract

Low-dimensional perovskites (LDP) are nowadays recognized as promising materials for the realization of highly performing photovoltaic cells. However, issues related to film morphology, composition, crystal quality and material homogeneity limit the device performances and reproducibility. In this work, we implement a robust method for the deposition of a LDP mixing methylammonium (MA) and phenylethylammonium (PEA) cations to create the mixed system (PEA)(2)MA(39)Pb(40)I(121) by using a two-step thermal annealing treatment (at 60 and 100 degrees C). Our approach results in LDP films with high crystal quality and enhanced carrier lifetime, which double the power conversion efficiency of reference devices, reaching up to 15 %.

199. Non‐Planar and Flexible Hole‐Transporting Materials from Bis‐Xanthene and Bis‐Thioxanthene Units for Perovskite Solar Cells

Author

Urieta‐Mora, Javier, García‐Benito, Inés, Zimmermann, Iwan, Aragó, Juan, García‐Fernández, Pedro D., Grancini, Giulia, Molina‐Ontoria, Agustín, Ortí, Enrique, Martín, Nazario, and Nazeeruddin, Mohammad Khaja

Abstract

Two new hole‐transporting materials (HTMs), BX‐OMeTAD and BTX‐OMeTAD , based on xanthene and thioxanthene units, respectively, and bearing p ‐methoxydiphenylamine peripheral groups, are presented for their use in perovskite solar cells (PSCs). The novelty of the newly designed molecules relies on the use of a single carbon‐carbon bond ‘C−C’ as a linker between the two functionalized heterocycles, which increases the flexibility of the molecule compared with the more rigid structure of the widely used HTM spiro‐OMeTAD. The new HTMs display a limited absorbance in the visible region, due to the lack of conjugation between the two molecular halves, and the chemical design used has a remarkably impact on the thermal properties when compared to spiro‐OMeTAD. BX‐OMeTAD and BTX‐OMeTAD have been tested in ([(FAPbI3)0.87(MAPbBr3)0.13]0.92[CsPbI3]0.08)‐based PSC devices exhibiting power conversion efficiencies of 14.19 and 16.55 %, respectively. The efficiencies reached, although lower than those measured for spiro‐OMeTAD (19.63 %), are good enough to consider the chemical strategy used as an interesting via to design HTMs for PSCs.

200. Molecular Engineering of Iridium Blue Emitters Using Aryl N-Heterocyclic Carbene Ligands

Author

Nazeeruddin, Mohammad Khaja, Aghazada, Sadig, Huckaba, Aron Joel, Pertegas Ojeda, Antonio, Babaei, Azin, Grancini, Giulia, Zimmermann, Iwan, and Bolink, Henk

Subjects
Luminescence, Nitrogen heterocycles, Carbenes, Iridium, Organic light-emitting diodes
Abstract

The synthesis of a new series of neutral bis[2-(2,4-difluorophen-2-yl)pyridine][1-(2-aryl)-3-methylimidazol-2-ylidene]iridium(III) complexes is reported. Each complex has been characterized by NMR spectroscopy, UV/Vis spectrophotometry, and cyclic voltammetry, and the photophysical properties examined in depth. Furthermore, two of the complexes have been characterized by single-crystal X-ray diffraction analysis. By systematically modifying the cyclometalating aryl group on the N-heterocyclic carbene (NHC) ligand from 2,4-dimethoxyphenyl to 6-methoxy-2-methyl-3-pyridyl, the energy levels of the Ir complexes were modified to produce new blue emitters with increased HOMO and triplet-state energies. OLED devices fabricated with these emitters showed external quantum efficiencies (EQEs) in the range of 2.3-3.2% with low turn-on values of 2.7-2.9 V and efficacies of up to 6.3%.

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