Targeted passivation and optimized interfacial carrier dynamics improving the efficiency and stability of hole transport layer-free narrow-bandgap perovskite solar cells

Xueqing Chang; Jun-Xing Zhong; Guo Yang; Ying Tan; Li Gong; Xing Ni; Yujin Ji; Youyong Li; Guodong Zhang; Yifan Zheng; Yuchuan Shao; Jie Zhou; Zhibin Yang; Lianzhou Wang; Wu-Qiang Wu

doi:10.1016/j.scib.2023.05.012

Targeted passivation and optimized interfacial carrier dynamics improving the efficiency and stability of hole transport layer-free narrow-bandgap perovskite solar cells

Sci Bull (Beijing). 2023 Jun 30;68(12):1271-1282. doi: 10.1016/j.scib.2023.05.012. Epub 2023 May 15.

Authors

Xueqing Chang¹, Jun-Xing Zhong¹, Guo Yang¹, Ying Tan¹, Li Gong², Xing Ni³, Yujin Ji³, Youyong Li³, Guodong Zhang⁴, Yifan Zheng⁴, Yuchuan Shao⁴, Jie Zhou⁵, Zhibin Yang⁵, Lianzhou Wang⁶, Wu-Qiang Wu⁷

Affiliations

¹ MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-sen University, Guangzhou 510006, China.
² Instrumental Analysis Research Center, Sun Yat-sen University, Guangzhou 510275, China.
³ Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, China.
⁴ Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
⁵ School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
⁶ Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane QLD 4072, Australia.
⁷ MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-sen University, Guangzhou 510006, China. Electronic address: wuwq36@mail.sysu.edu.cn.

PMID: 37258377
DOI: 10.1016/j.scib.2023.05.012

Abstract

Narrow-bandgap mixed Sn-Pb perovskite solar cells (PSCs) have showcased great potential to approach the Shockley-Queisser limit. Nevertheless, the practical application and long-term deployment of mixed Sn-Pb PSCs are still largely impeded by the rapid oxidation of Sn²⁺ ions and under-optimized carrier transport layer (CTL)/perovskite interfaces that would inevitably incur serious interfacial charge recombination and device performance degradation. Herein, we successfully removed the hole transport layer (HTL) by incorporating a small amount of organic phosphonic acid molecules into perovskites, which could preferably interact with Sn²⁺ ions (relative to Pb²⁺ analogues) at the grain boundaries (GBs) throughout the perovskite film thickness via coordination bonding, thus effectively retarding the oxidation of Sn²⁺, passivating the defects and suppressing the non-radiative recombination. Targeted modification effectively reinforced built-in potential by ∼100 mV, and favorably induced energy level cascade, thus accelerating spatial charge separation and facilitating the hole extraction from perovskite layer to underlying conductive electrodes even in the absence of HTL. Consequently, enhanced power conversion efficiencies up to 20.21% have been achieved, which is the record efficiency for the HTL-free mixed Sn-Pb PSCs, accompanied by a decent photovoltage of 0.87 V and improved long-term stability over 2400 h.

Keywords: Charge extraction; Defect passivation; Energy level; Perovskite solar cells; Sn-Pb perovskites.