Molecular Engineering of 2D Spacer Cations to Achieve Efficient and Stable 2D/3D Perovskite Solar Cells

Abstract

Introducing 2D perovskite onto the surface of 3D perovskite could not only passivate the defects in 3D perovskite, but also protect the 3D perovskite from humidity invasion, which could improve the device stability. The choice of spacer cations in 2D perovskites directly influences the overall properties of the 2D layer, which is crucial to the efficiency and stability of devices. Herein, trifluoromethyl benzylamine is developed as the 2D spacer cation, and the effects of –CF3 at different substitution positions on the surface morphology, carrier dynamics, and device performances are systematically investigated. Results show that the 3‐TFPMAI‐treated 2D/3D perovskite film shows smoother morphology, with fewer surface defects and less nonradiative recombination. Moreover, with a matched energy level, 3‐TFPMAI modification can accelerate hole extraction and hole transporting. The 3‐TFPMAI‐treated 2D/3D cell achieves a champion efficiency of 22.68%. What's more, the introduction of fluoride‐containing groups increases the hydrophobicity of the 2D layer, which effectively resists moisture erosion and greatly improves the long‐term and operational stability of the perovskite solar cells.

Management of the π-Conjugated System in Carbazole–Diphenylamine Derivative-Based Hole-Transporting Materials for Perovskite Solar Cells: Theoretical Simulation and Experimental Research

“…Perovskite solar cells (PSCs), as a new generation of photovoltaic technology, have achieved a remarkable power conversion efficiency (PCE) exceeding 26% . Perovskites possess unique light-capturing capabilities, extended diffusion lengths, a small band gap, and high charge carrier mobility, garnering widespread attention and in-depth research in the scientific community. − Typically, in conventional n–i–p-type PSCs, the perovskite active layer is situated between the hole transport layer (HTL) and the electron transport layer (ETL). Serving as the p-type interlayer atop the perovskite layer, hole transport materials (HTMs) can assist in suppressing the recombination of photogenerated charge carriers, facilitating the extraction and transfer of holes, and promoting the stability of PSCs. − Therefore, rational molecular design of HTMs is significant to obtain potential HTMs for improvement of PSC performance.…”