Thiourea with sulfur-donor as an effective additive for enhanced performance of lead-free double perovskite photovoltaic cells

Xiaoqing Yang; Huimin Xiang; Jianying Huang; Chuan Zhou; Ran Ran; Wei Wang; Wei Zhou; Zongping Shao

doi:10.1016/j.jcis.2022.07.165

Thiourea with sulfur-donor as an effective additive for enhanced performance of lead-free double perovskite photovoltaic cells

J Colloid Interface Sci. 2022 Dec 15;628(Pt A):476-485. doi: 10.1016/j.jcis.2022.07.165. Epub 2022 Jul 29.

Authors

Xiaoqing Yang¹, Huimin Xiang¹, Jianying Huang¹, Chuan Zhou¹, Ran Ran¹, Wei Wang², Wei Zhou¹, Zongping Shao³

Affiliations

¹ State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China.
² State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China. Electronic address: wangwei@njtech.edu.cn.
³ State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China; WA School of Mines: Minerals, Energy and Chemical Engineering (WASM-MECE), Curtin University, Perth, WA 6845, Australia. Electronic address: shaozp@njtech.edu.cn.

PMID: 35933866
DOI: 10.1016/j.jcis.2022.07.165

Abstract

Lead-free inorganic Cs₂AgBiBr₆ double perovskites have emerged as promising materials in perovskite solar cells (PSCs) to tackle the inferior stability and toxicity issues of organic-inorganic hybrid PSCs. However, the power conversion efficiencies (PCEs) of Cs₂AgBiBr₆ solar cells are remarkably restricted by the intrinsic and extrinsic defects of Cs₂AgBiBr₆ films. More specifically, the fast crystallization process in the formation of Cs₂AgBiBr₆ films strongly prevents the homogeneous growth of perovskite crystals, leading to inferior Cs₂AgBiBr₆ film quality. This work introduces a facile strategy to retard the crystallization of Cs₂AgBiBr₆ perovskites by introducing Lewis base additives into the precursor solution. The incorporation of a strongly coordinated thiourea additive with a sulfur donor leads to the generation of a Lewis acid base adduct, which retards the crystallization process for Cs₂AgBiBr₆ crystals, improves the quality of the Cs₂AgBiBr₆ film, decreases the defect density and inhibits charge carrier recombination. After optimization, the cell delivers a superior PCE of 3.07%, surpassing that reported for most Cs₂AgBiBr₆-based solar cells in the literature, and exhibits outstanding stability with a PCE retention rate of 95% after 20 days of storage in air. This work provides an effective strategy for further improvements in the performance of inorganic lead-free Cs₂AgBiBr₆-based photovoltaic cells.

Keywords: Cs(2)AgBiBr(6); Film quality optimization; Lead-free double perovskite; Perovskite solar cell; Thiourea additive.