All‐Inorganic CsPbI<sub>3</sub> Quantum Dot Solar Cells with Efficiency over 16% by Defect Control
Linlin Zhang, Cuiting Kang, Guizhi Zhang, Zhenxiao Pan, Zhaoshuai Huang, Shuaihang Xu, Huashang Rao, Hongbin Liu, Shengfan Wu, Xin Wu, Xiaosong Li, Zonglong Zhu, Xinhua Zhong, Alex K.‐Y. Jen
Abstract
Abstract All‐inorganic CsPbI 3 quantum dots (QDs) have shown great potential in photovoltaic applications. However, their performance has been limited by defects and phase stability. Herein, an anion/cation synergy strategy to improve the structural stability of CsPbI 3 QDs and reduce the pivotal iodine vacancy ( V I ) defect states is proposed. The Zn‐doped CsPbI 3 (Zn:CsPbI 3 ) QDs have been successfully synthesized employing ZnI 2 as the dopant to provide Zn 2+ and extra I − . Theoretical calculations and experimental results demonstrate that the Zn:CsPbI 3 QDs show better thermodynamic stability and higher photoluminescence quantum yield (PLQY) compared to the pristine CsPbI 3 QDs. The doping of Zn in CsPbI 3 QDs increases the formation energy and Goldschmidt tolerance factor, thereby improving the thermodynamic stability. The additional I − helps to reduce the V I defects during the synthesis of CsPbI 3 QDs, resulting in the higher PLQY. More importantly, the synergistic effect of Zn 2+ and I − in CsPbI 3 QDs can prevent the iodine loss during the fabrication of CsPbI 3 QD film, inhibiting the formation of new V I defect states in the construction of solar cells. Consequently, the anion/cation synergy strategy affords the CsPbI 3 quantum dot solar cells (QDSC) a power conversion efficiency over 16%, which is among the best efficiencies for perovskite QDSCs.