Robust Stability of Efficient Lead-Free Formamidinium Tin Iodide Perovskite Solar Cells Realized by Structural Regulation

Weiyin Gao; Chenxin Ran; Jingrui Li; Hua Dong; Bo Jiao; Lijun Zhang; Xuguang Lan; Xun Hou; Zhaoxin Wu

doi:10.1021/acs.jpclett.8b03194

Robust Stability of Efficient Lead-Free Formamidinium Tin Iodide Perovskite Solar Cells Realized by Structural Regulation

J Phys Chem Lett. 2018 Dec 20;9(24):6999-7006. doi: 10.1021/acs.jpclett.8b03194. Epub 2018 Dec 3.

Authors

Weiyin Gao¹, Chenxin Ran^{1

2}, Jingrui Li³, Hua Dong¹, Bo Jiao¹, Lijun Zhang⁴, Xuguang Lan⁵, Xun Hou¹, Zhaoxin Wu^{1

2}

Affiliations

¹ Key Laboratory of Photonics Technology for Information, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering , Xi'an Jiaotong University , Xi'an 710049 , P.R. China.
² Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan 030006 , China.
³ Department of Applied Physics , Aalto University , FI-00076 AALTO , Finland.
⁴ State Key Laboratory of Superhard Materials, Key Laboratory of Automobile Materials of MOE, and College of Materials Science and Engineering , Jilin University , Changchun 130012 , China.
⁵ Institute of Artificial Intelligence and Robotics , Xi'an Jiaotong University , Xi'an 710049 , China.

PMID: 30499301
DOI: 10.1021/acs.jpclett.8b03194

Abstract

The instability issue of Pb-free Sn-based perovskite is one of the biggest challenges for its application in optoelectronic devices. Herein, a structural regulation strategy is demonstrated to regulate the geometric symmetry of formamidiniumtin iodide (FASnI₃) perovskite. Experimental and theoretical works show that the introduction of cesium cation (Cs⁺) could improve the geometric symmetry, suppress the oxidation of Sn²⁺, and enhance the thermodynamical structural stability of FASnI₃. As a result, the inverted planar Cs-doped FASnI₃-based perovskite solar cell (PSC) is shown to maintain 90% of its initial power-conversion efficiency (PCE) after 2000 h stored in N₂, which is the best durability to date for 3D Sn-based PSCs. Most importantly, the air, thermal, and illumination stabilities of the PSCs are all improved after Cs doping. The PCE of the Cs-doped PSC shows a 63% increase compared to that of the control device (from 3.74% to 6.08%) due to the improved quality of the Cs-doped FASnI₃ film.