Ligand-Induced In Situ Epitaxial Growth of PbI2 Nanosheets/MAPbI3 Heterojunction Realizes High-Performance HTM-Free Carbon-Based MAPbI3 Solar Cells

Kaihang Sang; Dongqi Wu; Suxin Zhao; Huanyi Zhou; Junfang Zhang; Zhensang Tong; Feifei Ding; Qi Pang; Xinguo Zhang; Liya Zhou; Peican Chen

doi:10.1002/smtd.202301531

Ligand-Induced In Situ Epitaxial Growth of PbI₂ Nanosheets/MAPbI₃ Heterojunction Realizes High-Performance HTM-Free Carbon-Based MAPbI₃ Solar Cells

Small Methods. 2024 Feb 2:e2301531. doi: 10.1002/smtd.202301531. Online ahead of print.

Authors

Affiliations

¹ School of Chemistry and Chemical Engineering, Guangxi Key Laboratory of Electrochemical Energy Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Guangxi Colleges and Universities Key Laboratory of Applied Chemistry Technology and Resource Development, Guangxi University, Nanning, 530004, China.
² Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China.

PMID: 38308413
DOI: 10.1002/smtd.202301531

Abstract

Hole-transporting layer-free carbon-based perovskite solar cells (HTL-free C-PSCs) hold great promise for photovoltaic applications due to their low cost and outstanding stability. However, the low power conversion efficiency (PCE) of HTL-free C-PSCs mainly results from grain boundaries (GBs). Here, epitaxial growth is proposed to rationally design a hybrid nanostructure of PbI₂ nanosheets/perovskite with the desired photovoltaic properties. A post-treatment technique using tri(2,2,2-trifluoromethyl) phosphate (TFEP) to induce in situ epitaxial growth of PbI₂ nanosheets at the GBs of perovskite films realizes high-performance HTL-free C-PSCs. The structure model and high-resolution transmission electron microscope unravel the epitaxial growth mechanism. The epitaxial growth of oriented PbI₂ nanosheets generates the PbI₂ /perovskite heterojunction, which not only passivates defects but forms type-I band alignment, avoiding carrier loss. Additionally, Fourier-transform infrared spectroscopy, ³¹ P NMR, and ¹ H NMR spectra reveal the passivation effect and hydrogen bonding interaction between TFEP and perovskite. As a result, the V_OC is remarkably boosted from 1.04 to 1.10 V, leading to a substantial gain in PCE from 14.97% to 17.78%. In addition, the unencapsulated PSC maintains the initial PCE of 80.1% for 1440 h under air ambient of 40% RH. The work offers a fresh perspective on the rational design of high-performance HTL-free C-PSCs.

Keywords: PbI2 nanosheets; carbon electrodes; epitaxial growth; grain boundaries passivation; hydrogen bonds; perovskite solar cells.

Abstract

Grants and funding