Spencer T. Williams

Additive Enhanced Crystallization of Solution‐Processed Perovskite for Highly Efficient Planar‐Heterojunction Solar Cells

P.-W. Liang, C.-Y. Liao, Dr. C.-C. Chueh, Dr. F. Zuo, S. T. Williams, Dr. X.-K. Xin, Prof. A. K.-Y. Jen Department of Materials Science and Engineering University of Washington Seattle , WA 98195 , USA E-mail: ajen@u.washington.edu Prof. A. K.-Y. Jen Department of Chemistry University of Washington Seattle , WA 98195 , USA C.-Y. Liao, Prof. J. J. Lin Institute of Polymer Science and Engineering National Taiwan University Taipei 106 , Taiwan

High-Performance and Environmentally Stable Planar Heterojunction Perovskite Solar Cells Based on a Solution-Processed Copper-Doped Nickel Oxide Hole-Transporting Layer

An effective approach to significantly increase the electrical conductivity of a NiOx hole-transporting layer (HTL) to achieve high-efficiency planar heterojunction perovskite solar cells is demonstrated. Perovskite solar cells based on using Cu-doped NiOx HTL show a remarkably improved power conversion efficiency up to 15.40% due to the improved electrical conductivity and enhanced perovskite film quality. General applicability of Cu-doped NiOx to larger bandgap perovskites is also demonstrated in this study.

Integrated Molecular, Interfacial, and Device Engineering towards High‐Performance Non‐Fullerene Based Organic Solar Cells

High-performance non-fullerene OSCs with PCEs of up to ca. 6.0% are demonstrated based on PBDTT-F-TT polymer and a molecular di-PBI acceptor through comprehensive molecular, interfacial, and device engineering. Impressive PCEs can also be retained in devices with relatively thick BHJ layer and processed through non-halogenated solvents, indicating these high-performance non-fullerene OSCs are promising for large-area printing applications.

Role of Chloride in the Morphological Evolution of Organo-Lead Halide Perovskite Thin Films

A comprehensive morphological study was used to elucidate chlorides role in CH(3)NH(3)PbI(3-x)Cl(x) film evolution on a conducting polymer, PEDOT:PSS. Complex ion equilibria and aggregation in solution, as well as the role they play in nucleation, are found to ultimately be responsible for the unique morphological diversity observed in perovskite films grown in the presence of the chloride ion. An intermediate phase that is generated upon deposition and initial annealing templates continued self-assembly in the case of CH(3)NH(3)PbI(3-x)Cl(x). In the absence of chloride, the film growth of CH(3)NH(3)PbI(3) is directed by substrate interfacial energy. By employing the through-plane TEM analysis, we gain detailed insight into the unique crystallographic textures, grain structures, and elemental distributions across the breadth of films grown from precursor solutions with different chemistries. The lattice coherence seen in morphologies generated under the influence of chloride provides a physical rational for the enhancement in carrier diffusion length and lifetime.

Binary‐Metal Perovskites Toward High‐Performance Planar‐Heterojunction Hybrid Solar Cells

A simple, low temperature solution process for Pb/Sn binary-metal perovskite planar-heterojunction solar cells is demonstrated. Sn inclusion substantially influences the band-gap, crystallization kinetics, and thin-film formation leading to a broadened light absorption and enhanced film coverage on ITO/PEDOT:PSS. As a result, the optimized device shows a PCE exceeding 10%, which is the best result for binary-metal perovskite solar cells so far.

Low-temperature processed high-performance flexible perovskite solar cells via rationally optimized solvent washing treatments

High performance planar-heterojunction (PHJ) perovskite (CH3NH3PbI3) solar cells fabricated through low-temperature annealing are demonstrated. Simple spin-coating with an optimized solvent washing process readily forms homogeneous and crystalline perovskite thin films. The perovskite films fabricated via this solvent washing process show a low dependence on annealing temperature in achieving high crystallinity and large grain size, prerequisites for high efficiency perovskite solar cells. The solar cell device fabricated by solvent washing and 100 °C annealing exhibited a high power conversion efficiency (PCE) over 14% with high short circuit current density (JSC) of 19.3 mA cm−2 and fill factor (FF) of 0.80. More importantly, the device annealed at low temperature (<90 °C) also yields high PCEs of over 12%. This enables us to fabricate flexible solar cells at low-temperatures with promising PCE as high as 9.43%. This study demonstrates that this optimized solvent washing process is highly relevant for low-cost roll-to-roll (R-2-R) processing of high performance perovskite solar cells.

The roles of alkyl halide additives in enhancing perovskite solar cell performance

Alkyl halide additives have been investigated to elucidate their effects in enhancing perovskite solar cell performance. We found that the additives can participate in the perovskite formation via dissociated halides, suggesting that molecular structure of alkyl halide additives plays multiple roles in modulating the dynamics of perovskite crystal growth.

Current Challenges and Prospective Research for Upscaling Hybrid Perovskite Photovoltaics

Organic-inorganic hybrid perovskite photovoltaics (PSCs) are poised to push toward technology translation, but significant challenges complicating commercialization remain. Though J-V hysteresis and ecotoxicity are uniquely imposing issues at scale, CH3NH3PbI3 degradation is by far the sharpest limitation to the technologys potential market contribution. Herein, we offer a perspective on the practical market potential of PSCs, the nature of fundamental PSC challenges at scale, and an outline of prospective solutions for achieving module scale PSC production tailored to intrinsic advantages of CH3NH3PbI3. Although integrating PSCs into the energy grid is complicated by CH3NH3PbI3 degradation, the ability of PSCs to contribute to consumer electronics and other niche markets like those organic photovoltaics have sought footing in rests primarily upon the technologys price point. Thus, slot die, roll-to-roll processing has the greatest potential to enable PSC scale-up, and herein, we present a perspective on the research necessary to realize fully printable PSCs at scale.

Navigating Organo-Lead Halide Perovskite Phase Space via Nucleation Kinetics toward a Deeper Understanding of Perovskite Phase Transformations and Structure–Property Relationships

Organo-lead halide perovskite photovoltaics have developed faster than our understanding of the material itself. Using the vast body of work on perovskite processing created in just the past few years, it is possible to create a better picture of this materials complex phase-transformation behavior. This concept paper summarizes and correlates the current understanding of structural intermediates, kinetic controls, and structure-property relationships of organo-lead iodide perovskites. To this end, a new way of graphically relating information is developed, allowing the simultaneous mapping of schematic kinetic relationships between all currently prevailing perovskite deposition and growth techniques.

SrCl2 Derived Perovskite Facilitating a High Efficiency of 16% in Hole‐Conductor‐Free Fully Printable Mesoscopic Perovskite Solar Cells

Despite the breakthrough of over 22% power conversion efficiency demonstrated in organic-inorganic hybrid perovskite solar cells (PVSCs), critical concerns pertaining to the instability and toxicity still remain that may potentially hinder their commercialization. In this study, a new chemical approach using environmentally friendly strontium chloride (SrCl2 ) as a precursor for perovskite preparation is demonstrated to result in enhanced device performance and stability of the derived hole-conductor-free printable mesoscopic PVSCs. The CH3 NH3 PbI3 perovskite is chemically modified by introducing SrCl2 in the precursor solution. The results from structural, elemental, and morphological analyses show that the incorporation of SrCl2 affords the formation of CH3 NH3 PbI3 (SrCl2 )x perovskites endowed with lower defect concentration and better pore filling in the derived mesoscopic PVSCs. The optimized compositional CH3 NH3 PbI3 (SrCl2 )0.1 perovskite can substantially enhance the photovoltaic performance of the derived hole-conductor-free device to 15.9%, outperforming the value (13.0%) of the pristine CH3 NH3 PbI3 device. More importantly, the stability of the device in ambient air under illumination is also improved.