Compact Hole-selective Self-assembled Monolayers Enabled by Disassembling Micelles in Solution for Efficient Perovskite Solar Cells.

Self-assembled monolayers (SAMs) have been widely employed as effective hole-selective layers (HSLs) in inverted perovskite solar cells (PSCs). However, most SAM molecules are amphiphilic in nature and tend to form micelles in the commonly used alcoholic processing solvents. This introduces an extra energetic barrier to disassemble the micelles during the binding of SAM molecules on the substrate surface, limiting the formation of a compact SAM. To alleviate this problem for achieving optimal SAM growth, we develop a co-solvent strategy to disassemble the micelles of carbazole-based SAM molecules in the processing solution. This effectively increases the critical micelle concentration to be above the processing concentration and enhances the reactivity of the phosphonic acid anchoring group to allow densely packed SAMs to be formed on ITO. Consequently, the PSCs derived from using MeO-2PACz, 2PACz, and CbzNaph SAM HSLs showed universally improved performance, with the CbzNaph SAM derived device achieving a champion efficiency of 24.98% and improved stability. This article is protected by copyright. All rights reserved.