2D materials for conducting holes from grain boundaries in perovskite solar cells

Peng You,Naixiang Wang,Qidong Tai,Chun-Sing Lee,Chun-Ki Liu,Jiupeng Cao,Wei Lu,Dong Shen,Feng Yan,Yabing Qi,Zafer Hawash,Tsz-Wai Ng,Guanqi Tang

doi:10.1038/s41377-021-00515-8

Abstract

Grain boundaries in organic–inorganic halide perovskite solar cells (PSCs) have been found to be detrimental to the photovoltaic performance of devices. Here, we develop a unique approach to overcome this problem by modifying the edges of perovskite grain boundaries with flakes of high-mobility two-dimensional (2D) materials via a convenient solution process. A synergistic effect between the 2D flakes and perovskite grain boundaries is observed for the first time, which can significantly enhance the performance of PSCs. We find that the 2D flakes can conduct holes from the grain boundaries to the hole transport layers in PSCs, thereby making hole channels in the grain boundaries of the devices. Hence, 2D flakes with high carrier mobilities and short distances to grain boundaries can induce a more pronounced performance enhancement of the devices. This work presents a cost-effective strategy for improving the performance of PSCs by using high-mobility 2D materials.

Highlights

Perovskite solar cells (PSCs) based on organic–inorganic halide perovskites have been increasingly studied in recent years
The coverage of 2D flakes on the perovskite films was only several percent, most of the flakes were located on the perovskite Grain boundaries (GBs)
Due to the high carrier mobilities of 2D materials, especially black phosphorus (BP), the hole transfer from GBs was dramatically enhanced in PSCs, resulting in substantial improvements in the efficiency and stability of the devices

Summary

Introduction

Perovskite solar cells (PSCs) based on organic–inorganic halide perovskites have been increasingly studied in recent years. Organic–inorganic halide perovskites have shown many advantages over conventional semiconductors for photovoltaics, including long carrier lifetimes, high light absorption, easy processing and low fabrication cost[3,4,5,6,7,8,9,10,11]. Grain boundaries (GBs) in PSCs have been found to be detrimental to the photovoltaic performance of devices[12]. Numerous papers have reported that defects in perovskite GBs should be passivated by suitable materials, such as quaternary ammonium halide[13], fullerene derivatives[14,15,16] and CH3NH3I (MAI)[17], to alleviate carrier recombination and improve device performance. We report a novel method to overcome the drawback of perovskite GBs without passivating defects

Methods

Results

Conclusion