# Elucidating the long-range charge carrier mobility in metal halide perovskite thin films

## TL;DR

This paper introduces a combined optical and electrical measurement technique to accurately determine long-range charge carrier mobility in lead halide perovskite films, revealing significant differences based on fabrication methods.

## Contribution

A novel measurement approach that simultaneously evaluates conductivity and charge density to accurately assess lateral mobility in perovskite films.

## Key findings

- Lateral mobility in MAPbI3 is approximately 2 cm²/Vs.
- Mobility varies from 2.2 to 0.2 cm²/Vs across different fabrication methods.
- First accurate measurement of long-range charge mobility in lead halide perovskite films.

## Abstract

Many optoelectronic properties have been reported for lead halide perovskite polycrystalline films. However, ambiguities in the evaluation of these properties remain, especially for long-range lateral charge transport, where ionic conduction can complicate interpretation of data. Here we demonstrate a new technique to measure the long-range charge carrier mobility in such materials. We combine quasi-steady-state photo-conductivity measurements (electrical probe) with photo-induced transmission and reflection measurements (optical probe) to simultaneously evaluate the conductivity and charge carrier density. With this knowledge we determine the lateral mobility to be ~ 2 cm2/Vs for CH3NH3PbI3 (MAPbI3) polycrystalline perovskite films prepared from the acetonitrile/methylamine solvent system. Furthermore, we present significant differences in long-range charge carrier mobilities, from 2.2 to 0.2 cm2/Vs, between films of contemporary perovskite compositions prepared via different fabrication processes, including solution and vapour phase deposition techniques. Arguably, our work provides the first accurate evaluation of the long-range lateral charge carrier mobility in lead halide perovskite films, with charge carrier density in the range typically achieved under photovoltaic operation.

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Source: https://tomesphere.com/paper/1812.06322