Guanidium-assisted crystallization engineering for highly efficient CsPbI3 solar cells
Shuo Wang (Lanzhou University)
Youkui Xu (Lanzhou University)
Qian Wang (Lanzhou University)
Xufeng Zhou (Liaocheng University)
ZhenHua Li (Lanzhou University)
Meng Wang (Lanzhou University)
Yutian Lei (Lanzhou University)
Hong Zhang (Lanzhou University)
Haoxu Wang (TU Delft - Photovoltaic Materials and Devices)
Zhiwen Jin (Lanzhou University)
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Abstract
Iodine vacancies and uncoordinated iodide ions of CsPbI3 films are mainly responsible for nonradiative recombination. Here, we report a composition-engineering passivation method that through guanidium (GA+) and I− forms strong hydrogen bonds to passivate iodine vacancies and reduce defects. Both experimental and theoretical results confirmed strong chemical interactions between GA+ and uncoordinated I− in the GAxCs1−xPbI3 bulk or at the grain boundary. Moreover, GA+ doping could slow down the crystallization speed of perovskite films during the deposition process. As a result, we observed GA+ modified films with much lower defect density, larger grain size, and better carrier extraction and transportation. Upon GA+ passivation, the power conversion efficiency (PCE) is boosted from 18.01% to 19.05%, with open-circuit voltage (VOC) enhancement from 1.08 V to 1.14 V.