Cross-linked multifunctional bilayer polymer buffer for enhanced efficiency and stability in perovskite solar cells.

Li, Yuheng; Li, Lin; Zeng, Haipeng; Lan, Chunxiang; Yang, Shaomin; Zheng, Ziwei; Zeng, Miaomiao; Shi, Yingying et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Addressing the stability challenges induced by the chemical interactions between metal electrodes and perovskite components is essential for high-performance perovskite solar cells (PSCs). Herein, we design a bilayer multifunctional polymer buffer composed of polyethyleneimine (PEI) and 2-((2-methyl-3-(2-((2-methylbutanoyl)oxy)ethoxy)-3-oxopropyl)thio)-3-(methylthio)succinic acid (PDMEA), inserting into the interface of metal electrode/transporting layer. This buffer mitigates metal atom diffusion by forming thioether-metal-carboxyl chelation rings between the metal layer and PDMEA. Additionally, it facilitates efficient electron transport and suppresses interfacial recombination through an in-situ cross-linking between the carboxyl groups of PDMEA and the amine groups of PEI based on Lewis acid-base reaction. Consequently, this design effectively reduces undesirable metal/ion interdiffusion during device fabrication and operation. The resulting PSCs with the PEI/PDMEA buffer achieve certified power conversion efficiencies (PCEs) of 26.46% (0.1 cm<sup>2</sup>) and 24.70% (1.01 cm<sup>2</sup>), demonstrating enhanced thermal and operational stability. We anticipate that this buffer design strategy, which forms bilayer polymer buffers via cross-linking of polymers with distinct functionalities, will inspire the rational design of robust buffers for highly efficient and stable PSCs and other electronic devices.