Elimination of charge accumulation by a self-assembled cocrystal interlayer for efficient and stable perovskite solar cells

• Published in: Energy & environmental science 2024-01, Vol.17 (2), p.569-579
• Main Authors: Wang, Xueying, Zhong, Yang, Luo, Xiao, Sheng, Wangping, Yang, Jia, Tan, Licheng, Chen, Yiwang
• Format: Article
• Language: English
• Subjects: Accumulation; Bonding strength; Charge transfer; Energy conversion efficiency; Energy levels; Fluorine; Hydrogen bonding; Hydrogen bonds; Interfacial energy; Interlayers; Ion migration; Open circuit voltage; Perovskites; Photovoltaic cells; Relative humidity; Self-assembly; Solar cells; Stability; Tetracyanoquinodimethane
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d3ee03550f

Elimination of interfacial charge accumulation and inhibition of ion migration are still challenging for promoting both efficiency and operational stability of perovskite solar cells (PVSCs) with 2,2′,7,7′-tetrakis( N , N -di- p -methoxyphenyl-amine)-9,9′-spiro bifluorene (spiro-OMeTAD). Here an innovative interface engineering, self-assembled cocrystal layer (SAM-CL) for PVSCs is constructed from a 1-pyrenemethylamine hydrochloride (PRMA) monolayer on the perovskite surface and 2,3,5,6-tetrafluoro-7,7′,8,8′-tetracyanoquinodimethane (F4TCNQ) doped in spiro-OMeTAD through intermolecular π-π interactions and hydrogen bonds. SAM-CL optimizes interfacial energy level alignment by a strong charge-transfer effect, thereby eliminating interfacial charge accumulation. Moreover, the excellent barrier effect of large pyrene rings and fluorine atoms in SAM-CL effectively hinders ion migration and moisture invasion, thus significantly improving the stability of PVSCs. The resulting PVSCs yield a power conversion efficiency (PCE) of 24.03% with a high open circuit voltage of 1.21 V and deliver impressive stability, which can maintain 85% of initial PCE after over 1800 h in air with a relative humidity of 70-80% without encapsulation. A SAM-CL has been introduced in n-i-p perovskite solar cells to optimize interfacial energy level arrangement and eliminate interfacial charge accumulation. The large pyrene rings and F atoms of SAM-CL inhibit severe ion migration and moisture erosion, thus improving device stability.