# Defect‐Passivating and Dense Indolocarbazole‐Based Self‐Assembled Monolayers for Efficient Inverted Perovskite Solar Cells With over 26.1% Efficiency

## TL;DR

Researchers developed new self-assembled monolayers that improve the efficiency and stability of perovskite solar cells, achieving over 26% efficiency.

## Contribution

A novel strategy for designing indolocarbazole-based SAMs with optimized nitrogen positions and anchoring groups for high-performance solar cells.

## Key findings

- M3PAICz-1 SAMs achieved 26.12% power conversion efficiency in 1.55 eV bandgap PSCs.
- M3PAICz-1 SAMs also enabled 22.19% efficiency in wide-bandgap PSCs.
- The SAMs improved surface wettability, compactness, and defect passivation.

## Abstract

Self‐assembled monolayers (SAMs) are widely used in NiOx‐based inverted perovskite solar cells (PSCs). However, the poor wettability, low surface coverage, inhomogeneous distribution, and inadequate defect passivation capability of SAMs limit further improvements in the efficiency and stability of IPSCs. Herein, we have developed a series of indolocarbazole‐based SAMs, namely, D3PAICz‐1, M3PAICz‐1, D3PAICz‐2, and M3PAICz‐2. We systematically investigated how the nitrogen positions in indolocarbazole‐based SAMs and the anchoring group number synergistically influence device performance and stability. Among these SAMs, monophosphonate‐anchored M3PAICz‐1 demonstrates advantages in surface wettability, compactness, film uniformity, energy level alignment, hole extraction, and defect passivation. Consequently, the corresponding 1.55 eV bandgap PSCs achieved the highest power conversion efficiency (PCE) of 26.12% and excellent air stability. More interestingly, M3PAICz‐1 also endowed 1.68 eV wide‐bandgap (WBG) PSCs with an impressive efficiency of 22.19%, demonstrating its good universality as HTL. Our findings provide valuable insights for designing novel SAM molecules targeted at practical high‐performance PSCs.

This study proposes a strategy to modulate nitrogen positions (meta‐/para‐) in indolocarbazole units and the number of anchoring groups (mono‐/bis‐phosphonate), achieving a remarkable PCE of 26.12%, among the highest reported for PSCs using indolocarbazole‐based SAMs as HTLs.