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Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open‐circuit voltage, short‐circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application, and are put into perspective using, e.g., the detailed balance efficiency limit. The 3rd installment of the “Emerging PV reports” extends the scope toward triple junction solar cells.

Photodynamic therapy (PDT) is currently limited by the inability of photosensitizers (PSs) to enter cancer cells and generate sufficient reactive oxygen species. Utilizing phosphorescent triplet states of novel PSs to generate singlet oxygen offers exciting possibilities for PDT. Here, we report phosphorescent octahedral molybdenum (Mo)-based nanoclusters (NC) with tunable toxicity for PDT of cancer cells without use of rare or toxic elements. Upon irradiation with blue light, these molecules are excited to their singlet state and then undergo intersystem crossing to their triplet state. These NCs display surprising tunability of their cellular cytotoxicity and phototoxicity by modulating the apical halide ligand with a series of short chain fatty acids from trifluoroacetate to heptafluorobutyrate. The NCs are effective in PDT against breast, skin, pancreas, and colon cancer cells as well as their highly metastatic derivatives, demonstrating the robustness of these NCs in treating a wide variety of aggressive cancer cells. Furthermore, these NCs are internalized by cancer cells, remain in the lysosome, and can be modulated by the apical ligand to produce singlet oxygen. Thus, (Mo)-based nanoclusters are an excellent platform for optimizing PSs. Our results highlight the profound impact of molecular nanocluster chemistry in PDT applications.

Photodynamic therapy (PDT) has the potential to improve cancer treatment by providing dual selectivity through the use of both photoactive agent and light, with the goal of minimal harmful effects from either the agent or light alone. However, current PDT is limited by insufficient photosensitizers (PSs) that can suffer from low tissue penetration, insufficient phototoxicity (toxicity with light irradiation), or undesirable cytotoxicity (toxicity without light irradiation). Recently, we reported a platform for decoupling optical and electronic properties with counterions that modulate frontier molecular orbital levels of a photoactive ion. Here, we demonstrate the utility of this platform

Single-crystal inorganic halide perovskites are attracting interest for quantum device applications. Here we present low-temperature quantum magnetotransport measurements on thin film devices of epitaxial single-crystal CsSnBr$_{3}$, which exhibit two-dimensional Mott variable range hopping (VRH) and giant negative magnetoresistance. These findings are described by a model for quantum interference between different directed hopping paths and we extract the temperature-dependent hopping length of charge carriers, their localization length, and a lower bound for their phase coherence length of ~100 nm at low temperatures. These observations demonstrate that epitaxial halide perovskite devices are emerging as a material class for low-dimensional quantum coherent transport devices., 11 pages (main manuscript + SI), 12 figures (5 in manuscript, 7 in SI)

We report a significant Stokes shift enhancement in near-infrared fluorescing cyanines as a result of C4′-substitution with cyclic or acyclic amines. Based on a combined experimental and density functional study, a simple strategy for optimizing the Stokes shift is proposed. By tuning the relative energies of cyanine-like and bis-dipolar conformers, differing in the rotational angle of the amine substituent, it is possible to develop molecules that undergo conformational change upon excitation, resulting in a predictable Stokes shift.

Fair and meaningful device per- formance comparison among luminescent solar concentrator- photovoltaic (LSC-PV) reports cannot be realized without a gen- eral consensus on reporting stan- dards in LSC-PV research. There- fore, it is imperative to adopt standardized characterization protocols for these emerging types of PV devices that are consistent with other PV devices. This commentary highlights several common limitations in LSC literature and summarizes the best practices moving for- ward to harmonize with standard PV reporting, considering the greater nuances present with LSC-PV. Based on these prac- tices, a checklist of actionable items is provided to help stan- dardize the characterization/re- porting protocols and offer a set of baseline expectations for au- thors, reviewers, and editors. The general consensus combined with the checklist will ultimately guide LSC-PV research towards reliable and meaningful ad- vances.

Chenchen Yang joined the materials science program at Michigan State University in 2015 to work under Prof. Lunt in the Molecular and Organic Excitonics Lab. He earned his B.E. from the University of Electronic Science and Technology of China in 2012. Then he obtained his M.S. from the University of Florida in 2015. His current research focuses on transparent solar cell synthesis, fabrication, and characterization. Dianyi Liu obtained his Ph.D. in inorganic chemistry from Lanzhou University in 2009. He then worked as a postdoc at Peking University, the University of Saskatchewan, and Michigan State University. He began as an assistant professor at Westlake University in January 2019. His research interests include flexible electronics, optoelectronic materials, and devices. Richard R. Lunt is the Johansen Crosby Endowed Professor at Michigan State University in the Departments of Chemical Engineering & Materials Science and Physics. He earned his B.S. from the University of Delaware and his Ph.D. from Princeton University. He then worked as a post-doctoralresearcher at MIT. His group focuses on understanding and exploiting excitonic photophysics and molecular crystal growth to develop unique thin-film optoelectronic devices. He is known for his pioneering work on transparent solar cells and concentrators.

Photoactive agents are promising complements for both early diagnosis and targeted treatment of cancer. The dual combination of diagnostics and therapeutics is known as theranostics. Photoactive theranostic agents are activated by a specific wavelength of light and emit another wavelength, which can be detected for imaging tumors, used to generate reactive oxygen species for ablating tumors, or both. Photodynamic therapy (PDT) combines photosensitizer (PS) accumulation and site-directed light irradiation for simultaneous imaging diagnostics and spatially targeted therapy. Although utilized since the early 1900s, advances in the fields of cancer biology, materials science, and nanomedicine have expanded photoactive agents to modern medical treatments. In this review we summarize the origins of PDT and the subsequent generations of PSs and analyze seminal research contributions that have provided insight into rational PS design, such as photophysics, modes of cell death, tumor-targeting mechanisms, and light dosing regimens. We highlight optimizable parameters that, with further exploration, can expand clinical applications of photoactive agents to revolutionize cancer diagnostics and treatment.

This work uses a coupled modeling approach for evaluating the electricity production of vehicle-integrated photovoltaic (VIPV) systems with consideration of location-specific environmental conditions. We combine temperature-dependent electrical models with a heat transfer solver that allows the calculation of module temperatures and the irradiance incident on curved vehicle surfaces. The approach is used to compare the energy production of three different VIPV systems in five different locations in the United States.

Chenchen Yang joined the materials science program at Michigan State University in 2015 to work under Prof. Lunt in the Molecular and Organic Excitonics Lab. He earned his B.E. from the University of Electronic Science and Engineering of China in 2012. Then, he obtained his M.S. from University of Florida in 2015. His current research focuses on transparent solar cell synthesis, fabrication, and characterization. Dianyi Liu obtained his PhD in inorganic chemistry from Lanzhou University in 2009. He then worked as a postdoc at Peking University, the University of Saskatchewan, and Michigan State University. He began as an assistant professor at Westlake University in January 2019. His research interests include flexible electronics, optoelectronic materials, and devices. Matthew Bates is a graduate student in chemical engineering at Michigan State University working in the Molecular and Organic Excitonic Lab led by Prof. Lunt. He received his B.S. in chemical engineering from Oregon State University in 2016. He is focused on developing transparent photovoltaics. Miles Barr is co-founder and Chief Technology Officer at Ubiquitous Energy in Redwood City, CA. He earned his bachelor’s degree from Vanderbilt University and his Ph.D. from the Massachusetts Institute of Technology, both in chemical engineering. He then co-founded Ubiquitous Energy and has grown the company through pilot manufacturing, serving as both CEO and CTO. His team is currently working to develop, scale up, and commercialize transparent solar technology for a variety of end applications. Richard R. Lunt is the Johansen Crosby Endowed Professor at Michigan State University in the Departments of Chemical Engineering & Materials Science and Physics. He earned his B.S. from the University of Delaware and his PhD from Princeton University. He then worked as a post-doctoral researcher at MIT. His group focuses on understanding and exploiting excitonic photophysics and molecular crystal growth to develop unique thin-film optoelectronic devices. He is known for his pioneering work on transparent solar cells.

A full range of optoelectronic devices has been demonstrated incorporating hybrid organic-inorganic halide perovskites including high-performance photovoltaics, light emitting diodes, and lasers. Tin-based inorganic halide perovskites, such as CsSnX3 (X = Cl, Br, I), have been studied as promising candidates that avoid toxic lead halide compositions. One of the main obstacles for improving the properties of all-inorganic perovskites and transitioning their use to high-end electronic applications is obtaining crystalline thin films with minimal crystal defects, despite their reputation for defect tolerance in photovoltaic applications. In this study, the single-domain epitaxial growth of cesium tin iodide (CsSnI3) on closely lattice matched single-crystal potassium chloride (KCl) substrates is demonstrated. Using in situ real-time diffraction techniques, we find a new epitaxially-stabilized tetragonal phase at room temperature that expands the possibility for controlling electronic properties. We also exploit controllable epitaxy to grow multilayer two-dimensional quantum wells and demonstrate epitaxial films in a lateral photodetector architecture. This work provides insight into the phase control during halide perovskite epitaxy and expands the selection of epitaxially accessible materials from this exciting class of compounds.

Visibly transparent luminescent solar concentrators (TLSCs) can convert existing window glazing systems and non-window surfaces into solar energy harvesting resources, dramatically improving energy utilization efficiency. While there has been a significant interest in improving the power conversion efficiency, little attention has been focused on the challenges of integrating luminescent solar concentrators (LSCs) onto non-window surfaces or windows with significant infrared absorption coefficients. In these situations, the total internal reflection (TIR) can be effectively disabled when LSCs are directly and seamlessly integrated onto surfaces that are highly absorptive or scattering to infrared light. To overcome this challenge, we utilize a low refractive index adhesive film with high transparency between the TLSC waveguide and the back surface, to maintain both the device functionality and aesthetic quality of the surface underneath. Photovoltaic measurements were conducted to show that the TIR is re-enabled with the presence of such a structure. Thus, this method can effectively improve LSC performance and scalability, and allows TLSCs to be integrated onto arbitrary surfaces such as automobiles, billboards, and buildings.

Transparent photovoltaic (TPV) devices have a number of unique advantages compared with opaque photovoltaic devices. However, balancing efficiency and transparency has been difficult. To date, few ...

Summary Inorganic halide perovskites have emerged as a promising platform in a wide range of applications from solar energy harvesting to computing and light emission. The recent advent of epitaxial thin film growth of halide perovskites has made it possible to investigate low-dimensional quantum electronic devices based on this class of materials. This study leverages advances in vapor-phase epitaxy of halide perovskites to perform low-temperature magnetotransport measurements on single-domain cesium tin iodide (CsSnI3) epitaxial thin films. The low-field magnetoresistance carries signatures of coherent quantum interference effects and spin-orbit coupling. These weak anti-localization measurements reveal a micron-scale low-temperature phase coherence length for charge carriers in this system. The results indicate that epitaxial halide perovskite heterostructures are a promising platform for investigating long coherent quantum electronic effects and potential applications in spintronics and spin-orbitronics., Graphical abstract, Highlights • Epitaxial halide perovskites with extraordinary quantum phase coherence • Quantum transport properties with weak antilocalization observed in tetragonal CsSnI3 • Demonstration of quasi-2d charge carrier behavior with of spin-orbit coupling • Epitaxial halide perovskites emerging materials for quantum electronic applications, Quantum phenomena; Quantum physics; Quantum electronics; Electronic materials; Materials physics

Emerging photovoltaics (PVs), focuses on a variety of applications complementing large scale electricity generation. For instance, organic, dye-sensitized and some perovskite solar cells are considered in building integration, greenhouses, wearable and indoors, thereby motivating research on flexible, transparent, semitransparent, and multi-junction PVs. Nevertheless, it can be very time consuming to find or develop an up-to-date overview over the state-of-the-art performance for these systems and applications. Two important resources for record research cells efficiencies are the National Renewable Energy Laboratory chart and the efficiency tables compiled biannually by Martin Green and colleagues. Both publications provide an effective coverage over the established technologies, bridging research and industry. An alternative approach is proposed here summarizing the best reports in the diverse research subjects for emerging PVs. Best performance parameters are provided as a function of the photovoltaic bandgap energy for each technology and application, and are put into perspective using, e.g., the Shockley-Queisser limit. In all cases, the reported data correspond to published and/or properly described certified results, with enough details provided for prospective data reproduction. Additionally, the stability test energy yield (STEY) is included as an analysis parameter among state-of-the-art emerging PVs.

Emerging photovoltaics (PVs) focus on a variety of applications complementing large scale electricity generation. Organic, dye-sensitized, and some perovskite solar cells are considered in building integration, greenhouses, wearable, and indoor applications, thereby motivating research on flexible, transparent, semitransparent, and multi-junction PVs. Nevertheless, it can be very time consuming to find or develop an up-to-date overview of the state-of-the-art performance for these systems and applications. Two important resources for recording research cells efficiencies are the National Renewable Energy Laboratory chart and the efficiency tables compiled biannually by Martin Green and colleagues. Both publications provide an effective coverage over the established technologies, bridging research and industry. An alternative approach is proposed here summarizing the best reports in the diverse research subjects for emerging PVs. Best performance parameters are provided as a function of the photovoltaic bandgap energy for each technology and application, and are put into perspective using, e.g., the Shockley-Queisser limit. in all cases, the reported data correspond to published and/or properly described certified results, with enough details provided for prospective data reproduction. Additionally, the stability test energy yield is included as an analysis parameter among state-of-the-art emerging PVs., VDI/VD Innovation + Technik GmbH; SAOT - German Research Foundation (DFG)German Research Foundation (DFG); DFGGerman Research Foundation (DFG)European Commission [INST 90/917-1 FUGG, 182849149, SFB 953]; Energy Conversion Systems-from Materials to Devices [IGK 2495]; grant "ELF-PV-Design and development of solution processed functional materials for the next generations of PV technologies" [44-6521a/20/4]; grant "Solar Factory of the Future" [FKZ 20.2-3410.5-4-5]; SolTech Initiative by the Bavarian State Government; FAPESPFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2017/11986-5]; ShellRoyal Dutch Shell; ANP (Brazil's National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation; National Science FoundationNational Science Foundation (NSF) [CBET-1702591]; US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies OfficeUnited States Department of Energy (DOE) [34351]; European Research Council under the European Union's Horizon 2020 research and innovation program [742708]; Projekt DEAL, O.A. acknowledges the financial support from the VDI/VD Innovation + Technik GmbH (Project-title: PV-ZUM) and the SAOT funded by the German Research Foundation (DFG) in the framework of the German excellence initiative. C.J.B. acknowledges funding from DFG within INST 90/917-1 FUGG, the SFB 953 (DFG, project no. 182849149) and the IGK 2495 (Energy Conversion Systems-from Materials to Devices). C.J.B. further acknowledges the grants "ELF-PV-Design and development of solution processed functional materials for the next generations of PV technologies" (No. 44-6521a/20/4) and "Solar Factory of the Future" (FKZ 20.2-3410.5-4-5) and the SolTech Initiative by the Bavarian State Government. A.F.N. acknowledges support from FAPESP (Grant 2017/11986-5), Shell and the strategic importance of the support given by ANP (Brazil's National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. R.R.L. gratefully acknowledges support from the National Science Foundation under grant CBET-1702591. N.K. acknowledges funding by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office, Agreement Number 34351. J.N. thanks the European Research Council for support under the European Union's Horizon 2020 research and innovation program (grant agreement No 742708).; Open access funding enabled and organized by Projekt DEAL.

Visibly transparent luminescent solar concentrators (TLSCs) can optimize both power production and visible transparency by selectively harvesting the invisible portion of the solar spectrum. Since the primary applications of TLSCs include building envelopes, greenhouses, automobiles, signage, and mobile electronics, maintaining aesthetics and functionalities is as important as achieving high power conversion efficiencies (PCEs) in practical deployment. In this work, we combine massive-downshifting phosphorescent nanoclusters and fluorescent organic molecules into a TLSC system as ultraviolet (UV) and near-infrared (NIR) selective-harvesting luminophores, respectively, demonstrating UV and NIR dual-band selective-harvesting TLSCs with PCE over 3%, average visible transmittance (AVT) exceeding 75% and color metrics suitable for the window industry. With distinct wavelength-selectivity and effective utilization of the invisible portion of the solar spectrum, this work reports the highest light utilization efficiency (PCE x AVT) of 2.6 for a TLSC system, the highest PCE of any transparent photovoltaic device with AVT greater than 70%, and outperforms the practical limit for non-wavelength-selective transparent photovoltaics.

Metal halide nanoclusters represent an attractive class of molecular building blocks for the design of functional materials with superior optical properties that can be utilized in a range of applications. Here, we demonstrate red and near-infrared light emitting diodes with a maximum external quantum efficiency >1%, utilizing phosphorescent octahedral molybdenum iodide nanoclusters. Efficiency improvement in these devices is realized by substituting heavier ligands in the apical nanocluster position that lead to the improvement in photoluminescence and exciton formation efficiencies in the nanoclusters. These results highlight how modulation of nanocluster salts with key terminal ligands has a profound effect on photoluminescence as well as electrical injection.

Recombination dynamics of charge carriers in phosphorescent organic light emitting diodes (OLEDs) play an important role in performance metrics and device optimization even though very little is often known about these processes. In this work, we probe the recombination profile of OLEDs in-operando using spatially-positioned sensing layers. This method is used to investigate recombination in the emissive host and transport layer interfaces in a single emissive layer (EML) configuration and is extended to study the impact of double- and mixed-host EML architectures. Devices with the recombination distributed throughout the emissive layer show improved performance metrics, particularly in efficiency roll-off as compared to devices with the recombination pinned at the host/transport layer interfaces.

The increased awareness of greenhouse gas emissions on long-term climate trends has put the spotlight back on the development of renewable energy technologies to mitigate these processes. Solar based electricity generation has gained widespread recognition as a viable source of renewable energy but has been slowed by a number of factors including cost and available application areas. Luminescent solar concentrators (LSC) are being investigated as a low-cost route to expand solar energy harvesting into new spaces. With this demonstration, we develop kits for educating students about renewable and solar energy while promoting a sense of creativity often lacking in STEM demonstrations. Students design LSC devices by painting newly developed luminescent dyes on plastic waveguides. Thin solar cell strips are mounted around the edges of the LSC paintings to generate power. Creativity in design, a central part of scientific discovery and advancement, is promoted throughout the painting and testing of LSC materials.

Halide perovskite solar cells have seen dramatic progress in performance over the past several years. Certified efficiencies of inverted structure (p-i-n) devices have now exceeded 20%. In these p-i-n devices, fullerene compounds are the most popular electron-transfer materials. However, the full function of fullerenes in perovskite solar cells is still under investigation, and the mechanism of photocurrent hysteresis suppression by fullerene remains unclear. In previous reports, thick fullerene layers (>20 nm) were necessary to fully cover the perovskite film surface to make good contact with perovskite film and avoid large leakage currents. In addition, the solution-processed fullerene layer has been broadly thought to infiltrate into the perovskite film to passivate traps on grain boundary surfaces, causing suppressed photocurrent hysteresis. In this work, we demonstrate an efficient perovskite photovoltaic device with only 1 nm C60 deposited by vapor deposition as the electron-selective material. Util...

Organic molecular salts are an emerging and highly tunable class of materials for organic and transparent photovoltaics. In this work, we demonstrate novel phenyl borate and carborane-based anions paired with a near-infrared (NIR)-selective heptamethine cation. We further explore the effects of anion structures and functional groups on both device performance and physical properties. Changing the functional groups on the anion significantly alters the open circuit voltage and yields a clear dependence on electron withdrawing groups. Anion exchange is also shown to selectively alter the solubility and film surface energy of the resulting molecular salt, enabling the potential fabrication of solution-deposited cascade or multi-junction devices from orthogonal solvents. This study further expands the catalog and properties of organic salts for inexpensive, and stable NIR-selective molecular salt photovoltaics.

Solar energy offers a viable solution to our growing energy need. While adoption of conventional photovoltaics on rooftops and in solar farms has grown rapidly in the last decade, there is still plenty of opportunity for expansion. See-through solar technologies with partial light transmission developed over the past 30 years have initiated methods of integration not possible with conventional modules. The large-scale deployment necessary to offset global energy consumption could be further accelerated by developing fully invisible solar cells that selectively absorb ultraviolet and near-infrared light, allowing many of the surfaces of our built environment to be turned into solar harvesting arrays without impacting the function or aesthetics. Here, we review recent advances in photovoltaics with varying degrees of visible light transparency. We discuss the figures of merit necessary to characterize transparent photovoltaics, and outline the requirements to enable their widespread adoption in buildings, windows, electronic device displays, and automobiles. Transparency offers integration routes unavailable to opaque photovoltaics. Here, Lunt and co-workers review recent progress in transparent solar technologies, highlight technical challenges and measurement considerations, and review performance requirements for various applications.

In this article we review the development of organic salts integrated in organic photovoltaics (OPVs) and the potential capabilities that organic salts enable in OPV devices. Organic salts are ionic compounds composed of either organic cations, anions, or a combination of both. These organic salt semiconductors can exhibit highly tunable properties with absorption throughout the visible and deep into the near-infrared. These characteristics have enabled their integration into traditional OPV cells, multijunctions, and transparent photovoltaic devices with unique applications for windows and similar surfaces. We discuss the tunable properties of these salts that make them desirable for use in a range of applications and the historical development of salt based OPVs to provide an overview of the progress made in efficiencies and device architectures. Among their most exciting properties, organic salts have the ability to enable high efficiency transparent photovoltaics (TPVs), tunable energetics, and highly efficient ultra-deep infrared harvesting.

Effective artificial photosynthesis to produce hydrogen from water requires active, earth-abundant and low-cost electrocatalysts. In this communication, we present a novel electrodeposition method to produce Ni/Ni(OH)2 catalytic films in situ on conductive surfaces. The new method involves two cycles of cyclic voltammetry, and produces a catalytic film with a surface morphology consisting of a monolayer of firmly packed walnut-shaped particles. It has superior catalytic activity compared to catalysts produced by traditional electrodeposition methods under constant current density. The method is a simpler and more cost-effective way to fabricate highly-effective hydrogen evolution electrocatalysts, creating large numbers of Ni(OH)2/Ni interfaces that shift the catalyst's performance significantly towards that of platinum.

Light-activated theranostics offer promising opportunities for disease diagnosis, image-guided surgery, and site-specific personalized therapy. However, current fluorescent dyes are limited by low brightness, high cytotoxicity, poor tissue penetration, and unwanted side effects. To overcome these limitations, we demonstrate a platform for optoelectronic tuning, which allows independent control of the optical properties from the electronic properties of fluorescent organic salts. This is achieved through cation-anion pairing of organic salts that can modulate the frontier molecular orbital without impacting the bandgap. Optoelectronic tuning enables decoupled control over the cytotoxicity and phototoxicity of fluorescent organic salts by selective generation of mitochondrial reactive oxygen species that control cell viability. We show that through counterion pairing, organic salt nanoparticles can be tuned to be either nontoxic for enhanced imaging, or phototoxic for improved photodynamic therapy.

This work evaluates the energy benefit of transparent photovoltaics (TPV) for window application for two different donor materials. TPVs made of chloroaluminum phthalocyanine and heptamethine harvest energy from the near-infrared region of the spectrum and have the potential to reduce cooling energy. Due to the absorption property of the TPV material, energy-saving changes with location in the United States (U.S.). This work quantifies the energy savings using two types of TPVs in five types of commercial buildings and four different locations.

Visibly transparent luminescent solar concentrators (TLSC) have the potential to turn existing infrastructures into net-zero-energy buildings. However, the reabsorption loss currently limits the device performance and scalability. This loss is typically defined by the Stokes shift between the absorption and emission spectra of luminophores. In this work, the Stokes shifts (SS) of near-infrared selective-harvesting cyanines are altered by substitution of the central methine carbon with dialkylamines. We demonstrate varying SS with values over 80 nm and ideal infrared-visible absorption cutoffs. The corresponding TLSC with such modification shows a power conversion efficiency (PCE) of 0.4% for a >25 cm2 device area with excellent visible transparency >80% and up to 0.6% PCE over smaller areas. However, experiments and simulations show that it is not the Stokes shift that is critical, but the total degree of overlap that depends on the shape of the absorption tails. We show with a series of SS-modulated cyanine dyes that the SS is not necessarily correlated to improvements in performance or scalability. Accordingly, we define a new parameter, the overlap integral, to sensitively correlate reabsorption losses in any LSC. In deriving this parameter, new approaches to improve the scalability and performance are discussed to fully optimize TLSC designs to enhance commercialization efforts.

Visibly transparent luminescent solar concentrators (TLSCs) can optimize both power production and visible transparency by selectively harvesting the invisible portion of the solar spectrum. Since the primary applications of TLSCs include building envelopes, greenhouses, automobiles, signage, and mobile electronics, maintaining aesthetics and functionalities is as important as achieving high power conversion efficiencies (PCEs) in practical deployment. In this work, we combine massive-downshifting phosphorescent nanoclusters and fluorescent organic molecules into a TLSC system as ultraviolet (UV) and near-infrared (NIR) selective-harvesting luminophores, respectively, demonstrating UV and NIR dual-band selective-harvesting TLSCs with PCE over 3%, average visible transmittance (AVT) exceeding 75% and color metrics suitable for the window industry. With distinct wavelength-selectivity and effective utilization of the invisible portion of the solar spectrum, this work reports the highest light utilization efficiency (PCE x AVT) of 2.6 for a TLSC system, the highest PCE of any transparent photovoltaic device with AVT greater than 70%, and outperforms the practical limit for non-wavelength-selective transparent photovoltaics.

We demonstrate all thermal vapor-deposited CsSnBr 3 perovskite solar cells. The cell architecture consists of a planar CsSnBr 3 heterojunction where the perovskite layer is grown by thin sequential deposition of SnBr 2 and CsBr allowing for immediate reaction. While other halides of CsSnX 3 (e.g. X=Cl, I) are extremely air sensitive and change color within seconds, illumination tests performed on unencapsulated CsSnBr 3 devices in ambient air show no change over the span of hours. Further, we evaluate the impact of low-temperature annealing and incorporation of various fluoride passivating dopant profiles via vapor deposition. Our results demonstrate an exciting alternative pathway to develop all-inorganic lead-free perovskite photovoltaics.

A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells.

This Communication reports a new method for synthesizing manganese-based water oxidation catalysts in situ in aqueous media. The method provides powerful tunability of the electrodeposition process to enable independent control over the morphology of the catalytic film and the oxidation state of the catalyst. Our results show that the first cyclic voltammetry (CV) series produces a film with a nanoscale fibrous structure, whereas the second CV series improves its catalytic performance by enhancing the oxidation state of the film without damaging the existing surface morphology. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the MnOx film, CV was used to assess the catalyst functionality, and long-term amperometry was used to assess the stability.

Devices utilizing an entirely new class of earth abundant, inexpensive phosphorescent emitters based on metal-halide nanoclusters are reported. Light-emitting diodes with tunable performance are demonstrated by varying cation substitution to these nanoclusters. Theoretical calculations provide insight about the nature of the phosphorescent emitting states, which involves a strong pseudo-Jahn-Teller distortion.

Motivated by the exciting properties of metal halide perovskites in photovoltaic applications, there is an evolving need to further explore the limitations of this class of materials in broader fields and high end optoelectronics, which requires better control over the film structure, defect levels, and quality. Epitaxial growth has been ubiquitously deployed in the semiconducting industry. This affords routes to precisely align the atomic arrangement to control the structure and strain and achieve the highest levels of optoelectronic performance. In this review, the recent emergence and progress in the epitaxial growth of metal halide perovskites are introduced within the context of epitaxial and quasiepitaxial approaches, and recent advances are surveyed from growth methods to application integration. The main criteria distinguishing epitaxy and quasiepitaxy, i.e., lattice matching and ordering, can be deployed to direct the selection of proper substrates, growth methods, and precursors for various applications.

Organic single crystals are often shown to have significantly improved optoelectronic properties over polycrystalline thin films such as exciton diffusivity and carrier mobility. There is growing interest in incorporating such crystals in organic electronics despite a number of challenges. In this work, the homoepitaxial vapor phase growth modes for 9,10-diphenylanthracene (DPA) homoepitaxy are mapped as a function of growth rate and temperature using in situ ultra-low current reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), and atomic force microscopy (AFM). Vapor phase deposition was performed on free-standing single crystal DPA substrates, which show clear Kikuchi patterns. At room temperature, a transition from Frank-Van der Merwe layer-by-layer growth to step-flow growth is observed as the deposition rate is decreased, while at lower temperatures a Stranski-Krastanov layer-plus-island growth is observed. This is the first demonstration of true step-flow growth from room temperature vapor phase deposition for organic semiconductors and is reminiscent of traditional semiconductor growth regimes. Accordingly, these results could lead to improved control over growth and doping of organic single crystals, and lead to enhanced single crystal organic optoelectronic applications.