Strong self-trapping by deformation potential limits photovoltaic performance in bismuth double perovskite

Bo Wu; Weihua Ning; Qiang Xu; Manukumara Manjappa; Minjun Feng; Senyun Ye; Jianhui Fu; Stener Lie; Tingting Yin; Feng Wang; Teck Wee Goh; Padinhare Cholakkal Harikesh; Yong Kang Eugene Tay; Ze Xiang Shen; Fuqiang Huang; Ranjan Singh; Guofu Zhou; Feng Gao; Tze Chien Sum

doi:10.1126/sciadv.abd3160

Strong self-trapping by deformation potential limits photovoltaic performance in bismuth double perovskite

Sci Adv. 2021 Feb 17;7(8):eabd3160. doi: 10.1126/sciadv.abd3160. Print 2021 Feb.

Authors

Bo Wu^{1

2

3}, Weihua Ning⁴, Qiang Xu², Manukumara Manjappa^{2

5}, Minjun Feng², Senyun Ye², Jianhui Fu², Stener Lie⁶, Tingting Yin², Feng Wang⁴, Teck Wee Goh², Padinhare Cholakkal Harikesh⁶, Yong Kang Eugene Tay², Ze Xiang Shen^{2

5

7}, Fuqiang Huang³, Ranjan Singh², Guofu Zhou^{1

8}, Feng Gao⁹, Tze Chien Sum¹⁰

Affiliations

¹ Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China. tzechien@ntu.edu.sg feng.gao@liu.se guofu.zhou@m.scnu.edu.cn bowu@m.scnu.edu.cn.
² Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
³ CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China.
⁴ Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-581 83, Sweden.
⁵ Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
⁶ Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, X-Frontier Block Level 5, 50 Nanyang Drive, Singapore 637553, Singapore.
⁷ CINTRA CNRS/NTU/Thales, UMI 3288, 50 Nanyang Drive, Singapore 637553, Singapore.
⁸ Shenzhen Guohua Optoelectronics Technology Co. Ltd., Shenzhen 518110, P. R. China.
⁹ Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-581 83, Sweden. tzechien@ntu.edu.sg feng.gao@liu.se guofu.zhou@m.scnu.edu.cn bowu@m.scnu.edu.cn.
¹⁰ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore. tzechien@ntu.edu.sg feng.gao@liu.se guofu.zhou@m.scnu.edu.cn bowu@m.scnu.edu.cn.

Abstract

Bismuth-based double perovskite Cs₂AgBiBr₆ is regarded as a potential candidate for low-toxicity, high-stability perovskite solar cells. However, its performance is far from satisfactory. Albeit being an indirect bandgap semiconductor, we observe bright emission with large bimolecular recombination coefficient (reaching 4.5 ± 0.1 × 10^-11 cm³ s^-1) and low charge carrier mobility (around 0.05 cm² s^-1 V^-1). Besides intermediate Fröhlich couplings present in both Pb-based perovskites and Cs₂AgBiBr₆, we uncover evidence of strong deformation potential by acoustic phonons in the latter through transient reflection, time-resolved terahertz measurements, and density functional theory calculations. The Fröhlich and deformation potentials synergistically lead to ultrafast self-trapping of free carriers forming polarons highly localized on a few units of the lattice within a few picoseconds, which also breaks down the electronic band picture, leading to efficient radiative recombination. The strong self-trapping in Cs₂AgBiBr₆ could impose intrinsic limitations for its application in photovoltaics.

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