Stabilized hole-selective layer for high-performance inverted p-i-n perovskite solar cells

19 Oct 2023

Published on Science (19 October 2023)

Author(s): Zhen Li, Xianglang Sun, Xiaopeng Zheng, Bo Li, Danpeng Gao, Shoufeng Zhang, Xin Wu, Shuai Li, Jianqiu Gong, Joseph M. Luther, Zhong’an Li, Zonglong Zhu

Abstract

P-i-n geometry perovskite solar cells (PSCs) offer simplified fabrication, greater amenability to charge extraction layers, and low-temperature processing over n-i-p counterparts. Self-assembled monolayers (SAMs) can enhance the performance of p-i-n PSCs but ultrathin SAMs can be thermally unstable. We report a thermally robust hole-selective layer comprised of nickel oxide (NiO_x) nanoparticle film with a surface-anchored (4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (MeO-4PADBC) SAM that can improve and stabilize the NiO_x/perovskite interface. The energetic alignment and favorable contact and binding between NiO_x/MeO-4PADBC and perovskite reduced the voltage deficit of PSCs with various perovskite compositions and led to strong interface toughening effects under thermal stress. The resulting 1.53–electron-volt devices achieved 25.6% certified power conversion efficiency and maintained >90% of their initial efficiency after continuously operating at 65 degrees Celsius for 1200 hours under 1-sun illumination.

Fig. 1. Molecular structure and electrical properties of HSLs.

Molecular structure and side view of (A) MeO-2PACz and (B) MeO-4PADBC. (C) Schematic illustration of MeO-4PADBC anchoring on NiO_x nanoparticle as the HSL in PSC. (D) FTIR spectra of MeO-4PADBC and NiO_x/MeO-4PADBC. (E) UPS spectra of ITO substrates covered by NiO_x, MeO-4PADBC, and NiO_x/MeO-4PADBC. (Left) UPS spectra around the secondary electron cutoff (WF, work function); (right) UPS spectra in the valence band (VB) region. (F) Schematic representation of the band edge positions of the studied HSLs based on values from UPS measurements, referenced to the vacuum level. E_F and E_VAC represent Fermi and vacuum levels, respectively. E_VBM and E_CBM represent the energy of valence band maximum and conduction band minimum, respectively.