Domain Walls Conductivity in Hybrid Organometallic Perovskites: The Key of CH3NH3PbI3 Solar Cell High Performance

TL;DR

This study demonstrates that charged domain walls in CH3NH3PbI3 perovskites exhibit significantly increased conductivity, which may explain the high efficiency of perovskite solar cells and suggest new ways to improve their performance.

Contribution

The paper provides a theoretical analysis of static conductivity at charged domain walls in organometallic perovskites, revealing a potential mechanism for high solar cell efficiency.

Findings

Conductivity at domain walls can increase by 3-4 orders of magnitude.

Formation of a highly mobile two-dimensional charge carrier gas at the walls.

High conductivity explains the efficiency of defect-rich perovskite films.

Abstract

The past several years has witnessed a surge of interest in organometallic trihalide perovskites, which are at the heart of the new generation of solid-state solar cells. Here, we calculated the static conductivity of charged domain walls in n- and p- doped organometallic uniaxial ferroelectric semiconductor perovskite CH3NH3PbI3 using the Landau-Ginzburg-Devonshire (LGD) theory. We find that due to the charge carrier accumulation, the static conductivity may drastically increase at the domain wall by 3-4 orders of magnitude in comparison with conductivity through the bulk of the material. Also, a two-dimensional degenerated gas of highly mobile charge carriers could be formed at the wall. The high values of conductivity at domain walls and interfaces explain high efficiency in organometallic solution-processed perovskite films which contains lots of different point and extended defects. These results could suggest new routes to enhance the performance of this promising class of novel photovoltaic materials.