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1. Impact of PbI 2 Passivation and Grain Size Engineering in CH 3 NH 3 PbI 3 Solar Absorbers as Revealed by Carrier‐Resolved Photo‐Hall Technique

   https://doi.org/10.1002/aenm.201902706  

   Euvrard, Julie ; Gunawan, Oki ; Mitzi, David B. ( November 2019 , Advanced Energy Materials)

   With power conversion efficiencies now exceeding 25%, hybrid perovskite solar cells require deeper understanding of defects and processing to further approach the Shockley‐Queisser limit. One approach for processing enhancement and defect reduction involves additive engineering—, e.g., addition of MASCN (MA = methylammonium) and excess PbI₂have been shown to modify film grain structure and improve performance. However, the underlying impact of these additives on transport and recombination properties remains to be fully elucidated. In this study, a newly developed carrier‐resolved photo‐Hall (CRPH) characterization technique is used that gives access to both majority and minority carrier properties within the same sample and over a wide range of illumination conditions. CRPH measurements on n‐type MAPbI₃films reveal an order of magnitude increase in carrier recombination lifetime and electron density for 5% excess PbI₂added to the precursor solution, with little change noted in electron and hole mobility values. Grain size variation (120–2100 nm) and MASCN addition induce no significant change in carrier‐related parameters considered, highlighting the benign nature of the grain boundaries and that excess PbI₂must predominantly passivate bulk defects rather than defects situated at grain boundaries. This study offers a unique picture of additive impact on MAPbI₃optoelectronic properties as elucidated by the new CRPH approach.

    

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2. Light-Induced Transient Lattice Dynamics and Metastable Phase Transition in CH 3 NH 3 PbI 3 Nanocrystals

   https://doi.org/10.1021/acsnano.2c06950  

   Leonard, Ariel A. ; Diroll, Benjamin T. ; Flanders, Nathan C. ; Panuganti, Shobhana ; Brumberg, Alexandra ; Kirschner, Matthew S. ; Cuthriell, Shelby A. ; Harvey, Samantha M. ; Watkins, Nicolas E. ; Yu, Jin ; et al ( March 2023 , ACS Nano)
3. Enhanced Grain Size and Crystallinity in CH 3 NH 3 PbI 3 Perovskite Films by Metal Additives to the Single-Step Solution Fabrication Process

   https://doi.org/10.1557/adv.2018.413  

   Almutawah, Zahrah S. ; Watthage, Suneth C. ; Song, Zhaoning ; Ahangharnejhad, Ramez H. ; Subedi, Kamala K. ; Shrestha, Niraj ; Phillips, Adam B. ; Yan, Yanfa ; Ellingson, Randy J. ; Heben, Michael J. ( January 2018 , MRS Advances)

   ABSTRACT Methods of obtaining large grain size and high crystallinity in absorber materials play an important role in fabrication of high-performance methylammonium lead iodide (MAPbI 3 ) perovskite solar cells. Here we study the effect of adding small concentrations of Cd 2+ , Zn 2+ , and Fe 2+ salts to the perovskite precursor solution used in the single-step solution fabrication process. Enhanced grain size and crystallinity in MAPbI 3 films were obtained by using 0.1% of Cd 2+ or Zn 2+ in the precursor solution. Consequently, solar cells constructed with Cd- and Zn-doped perovskite films show a significant improvement in device performance. These results suggest that the process may be an effective and facile method to fabricate high-efficiency perovskite photovoltaic devices. 

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4. Enhancing Chemical Stability and Suppressing Ion Migration in CH 3 NH 3 PbI 3 Perovskite Solar Cells via Direct Backbone Attachment of Polyesters on Grain Boundaries

   https://doi.org/10.1021/acs.chemmater.0c00995  

   Zhou, Yuchen ; Yin, Yifan ; Zuo, Xianghao ; Wang, Likun ; Li, Tai-De ; Zhou, Yuanyuan ; Padture, Nitin P. ; Yang, Zhenhua ; Guo, Yichen ; Xue, Yuan ; et al ( June 2020 , Chemistry of Materials)
5. Bismuth Enhances the Stability of CH 3 NH 3 PbI 3 (MAPI) Perovskite under High Humidity

   https://doi.org/10.1021/acs.jpcc.8b11674  

   Siegler, Timothy D. ; Houck, Daniel W. ; Cho, Shin Hum ; Milliron, Delia J. ; Korgel, Brian A. ( December 2018 , The Journal of Physical Chemistry C)