Large diffusion lengths of excitons in perovskite and ${\it TiO_2}$ heterojunction

TL;DR

This paper explains the large diffusion lengths of excitons in perovskite/${ m TiO_2}$ heterojunctions, attributing it to planar diffusion of indirect excitons, which enhances solar cell efficiency.

Contribution

It provides a theoretical analysis of exciton diffusion in perovskite heterojunctions, revealing the role of indirect excitons in increasing diffusion lengths.

Findings

Transport mean free path analyzed in heterojunctions

Large diffusion length due to planar diffusion of indirect excitons

Coupled system diffusion length exceeds single carrier length by orders

Abstract

Solar cells based on organometal halide perovskites have recently become very promising among other materials because of their cost-effective character and improvements in efficiency. Such performance is primarily associated with effective light absorption and large diffusion length of charge carriers. Our paper is devoted to the explanation of large diffusion lengths in these systems. The transport mean free path of charged carriers in a perovskite/${\it TiO_2}$ heterojunction that is an important constituent of the solar cells have been analyzed. Large transport length is explained by the planar diffusion of indirect excitons. Diffusion length of the coupled system increases by several orders compared to single carrier length due to the correlated character of the effective field acting on the exciton.