Complementary self-assembled monolayers enabling improved energy level alignment in inverted perovskite solar cells

Shantao Zhang, Xiaofen Jiang, Xue Wang, Yan Gao, TianAo Hou, Xiaoqian Teng, Haolin Wang, Wenjing Chen, Shuang Gao, Xinyu Li, Ziqi Hu*, Xiaojun Wu, Zhengguo Xiao, Tao Chen, Yanwu Zhu, Yalin Lu, Xiaocheng Zeng, Zonglong Zhu*, Shangfeng Yang*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

2 Citations (Scopus)

Abstract

Self-assembled monolayers (SAMs) have been commonly employed as hole-selective layers (HSLs) in inverted (p-i-n) perovskite solar cells (PSCs), and typically only a single-component SAM is applied, which plays limited role in selective hole transport. Herein, we synthesize a novel SAM, (4-(3,11-dibromo-7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (Br-4PADBC), and apply it as a complementary component to the commonly used [2-(3,6-dimeth oxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) SAM, accomplishing boosted hole transport in inverted PSCs. A series of characterizations and theoretical calculations are employed to unravel the roles of each components within the binary SAM (bi-SAM). The involvements of the non-planar dibenzo[c,g]carbazole unit and electron-withdrawing Br atoms induce larger dipole moment of Br-4PADBC than MeO-2PACz, resulting in much deeper work function of ITO and consequently improved alignment with the valence band energy level of perovskite. Besides, the introduced Br atoms improve the quality of perovskite crystals and help passivate defects of perovskite. On the other hand, the existence of the conventional MeO-2PACz SAM ensures the considerable conductivity of the bi-SAM and thus efficient hole extraction from the perovskite layer. As a result, inverted PSC devices based on bi-SAM HSL deliver a decent power conversion efficiency (PCE) of 24.52% as well as dramatically improved thermal and operational stabilities. © 2025 Science Press.
Original languageEnglish
Pages (from-to)136-145
JournalJournal of Energy Chemistry
Volume104
Online published6 Jan 2025
DOIs
Publication statusPublished - May 2025

Research Keywords

  • Dibenzo[c,g]carbazole
  • Dipole moment
  • Hole-selective layer
  • Perovskite solar cells
  • Self-assembled monolayer

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