Overcoming Short-Circuit in Lead-Free CH3NH3SnI3 Perovskite Solar Cells via Kinetically Controlled Gas–Solid Reaction Film Fabrication Process

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• 作者：Takamichi Yokoyama ; Duyen H. Cao ; Constantinos C. Stoumpos ; Tze-Bin Song ; Yoshiharu Sato ; Shinji Aramaki ; Mercouri G. Kanatzidis
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：March 3, 2016
• 年：2016
• 卷：7
• 期：5
• 页码：776-782
• 全文大小：362K
• ISSN：1948-7185

文摘

The development of Sn-based perovskite solar cells has been challenging because devices often show short-circuit behavior due to poor morphologies and undesired electrical properties of the thin films. A low-temperature vapor-assisted solution process (LT-VASP) has been employed as a novel kinetically controlled gas–solid reaction film fabrication method to prepare lead-free CH₃NH₃SnI₃ thin films. We show that the solid SnI₂ substrate temperature is the key parameter in achieving perovskite films with high surface coverage and excellent uniformity. The resulting high-quality CH₃NH₃SnI₃ films allow the successful fabrication of solar cells with drastically improved reproducibility, reaching an efficiency of 1.86%. Furthermore, our Kelvin probe studies show the VASP films have a doping level lower than that of films prepared from the conventional one-step method, effectively lowering the film conductivity. Above all, with (LT)-VASP, the short-circuit behavior often obtained from the conventional one-step-fabricated Sn-based perovskite devices has been overcome. This study facilitates the path to more successful Sn-perovskite photovoltaic research.