@misc{KediaRaiPhirkeetal., author = {Kedia, Mayank and Rai, Monika and Phirke, Himanshu and Aranda, Clara A. and Das, Chittaranjan and Chirvony, Vladimir and Boehringer, Stephan and Kot, Małgorzata and Malekshahi Byranvand, Mahdi and Flege, Jan Ingo and Redinger, Alex and Saliba, Michael}, title = {Light Makes Right: Laser Polishing for Surface Modification of Perovskite Solar Cells}, series = {ACS Energy Letters}, volume = {8}, journal = {ACS Energy Letters}, issn = {2380-8195}, doi = {10.1021/acsenergylett.3c00469}, pages = {2603 -- 2610}, abstract = {Interface engineering is a common strategy for passivating surface defects to attain open circuit voltages (Voc) in perovskite solar cells (PSCs). In this work, we introduce the concept of polishing a perovskite thin-film surface using a nanosecond (ns) pulsed ultraviolet laser to reduce surface defects, such as dangling bonds, undesirable phases, and suboptimal stoichiometry. A careful control of laser energy and scanning speed improves the photophysical properties of the surface without compromising the thickness. Using laser polishing, a Voc of 1.21 V is achieved for planar PSCs with a triple cation composition, showing an improved perovskite/hole transport interface by mitigating surface recombination losses. We measure an efficiency boost from 18.0\% to 19.3\% with improved stability of up to 1000 h. The results open the door to a new class of surface modification using lasers for interface passivation in well-controllable, automated, scalable, and solvent-free surface treatments.}, language = {en} } @misc{ZuoMalekshahiByranvandKodalleetal., author = {Zuo, Weiwei and Malekshahi Byranvand, Mahdi and Kodalle, Tim and Zohdi, Mohammadreza and Lim, Jaekeun and Carlsen, Brian and Friedlmeier, Theresa Magorian and Kot, Małgorzata and Das, Chittaranjan and Flege, Jan Ingo and Zong, Wansheng and Abate, Antonio and Sutter-Fella, Carolin M. and Li, Meng and Saliba, Michael}, title = {Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization}, series = {Advanced Materials}, volume = {35}, journal = {Advanced Materials}, number = {39}, issn = {0935-9648}, doi = {10.1002/adma.202302889}, abstract = {The most efficient and stable perovskite solar cells (PSCs) are made from a complex mixture of precursors. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g., by vacuum, an airstream, or a so-called antisolvent. Unfortunately, most oversaturation triggers do not expel the lingering (and highly coordinating) dimethyl sulfoxide (DMSO), which is used as a precursor solvent, from the thin films; this detrimentally affects long-term stability. In this work, (the green) dimethyl sulfide (DMS) is introduced as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, MAPbI3 PSCs are processed, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6\% efficiency, among the highest reported efficiencies for this system. To confirm the universality of the strategy, DMS is tested for FAPbI3 as another composition, which shows higher efficiency of 23.5\% compared to 20.9\% for a device fabricated with chlorobenzene. This work provides a universal strategy to control perovskite crystallization using coordination chemistry, heralding the revival of perovskite compositions with pure DMSO.}, language = {en} } @misc{ZiaMalekshahiByranvandRudolphetal., author = {Zia, Waqas and Malekshahi Byranvand, Mahdi and Rudolph, Toby and Rai, Monika and Kot, Małgorzata and Das, Chittaranjan and Kedia, Mayank and Zohdi, Mohammadreza and Zuo, Weiwei and Yeddu, Vishal and Saidaminov, Makhsud I. and Flege, Jan Ingo and Kirchartz, Thomas and Saliba, Michael}, title = {MAPbCl3 Light Absorber for Highest Voltage Perovskite Solar Cells}, series = {ACS Energy Letters}, volume = {9}, journal = {ACS Energy Letters}, issn = {2380-8195}, doi = {10.1021/acsenergylett.3c02777}, pages = {1017 -- 1024}, abstract = {Perovskite solar cells (PSCs) excel in achieving high open-circuit voltages (VOC) for narrow bandgaps (∼1.6 eV) but face challenges with wide-bandgap perovskites, like methylammonium lead trichloride (MAPbCl3) with a 3.03 eV bandgap. These materials are transparent in visible absorbing ultraviolet (UV) light. However, achieving uniform film crystallization remains a hurdle. Here, we enhance MAPbCl3 crystallization by manipulating annealing atmospheres (nitrogen, air, and MACl vapor). Excess MACl vapor improves surface coverage, which is crucial for film stability. We demonstrate that the microstructure of the perovskite film, including surface morphology, grain boundaries, and interfaces, can affect the photovoltaic properties. The subsequently obtained VOC of 1.78 V is the highest recorded for single-junction PSCs to the best of our knowledge. Surprisingly, the conventional hole-transport layer spiro-OMeTAD, optimized for narrow bandgaps, sustains such high voltages. Photoluminescence measurements reveal a trap-assisted recombination peak at 1.65 eV, indicating deep traps as significant to voltage loss in MAPbCl3.}, language = {en} }