A Gradient Heterostructure Based on Tolerance Factor in High‐Performance Perovskite Solar Cells with 0.84 Fill Factor. Issue 5 (28th November 2018)

• Record Type: Journal Article
• Authors: Qiao, Hong Wei; Yang, Shuang; Wang, Yun; Chen, Xiao; Wen, Tian Yu; Tang, Li Juan; Cheng, Qilin; Hou, Yu; Zhao, Huijun; Yang, Hua Gui
• Is Part Of: Advanced materials. Volume 31:Issue 5(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-11-28
• Subjects: charge transfer -- fill factor -- gradient heterostructures -- perovskite solar cells -- tolerance factor; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201804217
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: A gradient heterosturcture is one of the basic methods to control the charge flow in perovskite solar cells (PSCs). However, a classical route for gradient heterosturctures is based on the diffusion technique, in which the guest ions gradually diffuse into the films from a concentrated source of dopants. The gradient heterosturcture is only accessible to the top side, and may be time consuming and costly. Here, the "intolerant" n‐type heteroatoms (Sb 3+, In 3+ ) with mismatched cation sizes and charge states can spontaneously enrich two sides of perovskite thin films. The dopants at specific sides can be extracted by a typical hole‐transport layer. Theoretical calculations and experimental observations both indicate that the optimized charge management can be attributed to the tailored band structure and interfacial electronic hybridization, which promote charge separation and collection. The strategy enables the fabrication of PSCs with a spontaneous graded heterojunction showing high efficiency. A champion device based on Sb 3+ doped film shows a stabilized power‐conversion efficiency of 21.04% with a high fill factor of 0.84 and small hysteresis. Abstract : Trivalent cations (Sb 3+ and In 3+ ) can be spontaneously distributed with a gradient in organometal halide perovskites from homogeneous precursors, because of their difference in ionic size and electrostatic interaction between the dopants and the host atoms. This phenomenon can facilitate charge separation and collection of photoelectrons, leading to excellent photovoltaic performance.