Are Mobilities in Hybrid Organic-Inorganic Halide Perovskites Actually 'High'?

TL;DR

This paper critically examines the actual carrier mobilities in hybrid organic-inorganic perovskites used in solar cells, revealing they are lower than often claimed and exploring underlying scattering mechanisms affecting their performance.

Contribution

The study provides a combined experimental and theoretical analysis of carrier mobilities in HOIPs, challenging the notion of their high mobility and investigating scattering processes at room temperature.

Findings

Mobilities in HOIPs are lower than typically reported.

Electron-lattice interactions, such as acoustic phonons and polarons, influence carrier scattering.

Understanding these mechanisms can help improve HOIP solar cell efficiency.

Abstract

We present an experimental and theoretical viewpoint on the electronic carrier mobilities of typical hybrid organic-inorganic perovskites (HOIPs). While these mobilities are often quoted as high, a review of them shows that although otherwise the semiconducting properties of HOIPs are impressively good, mobilities of HOIPs used in most solar cells are actually not that high. This is especially apparent if they are compared to those of inorganic semiconductors used in other high efficiency solar cells. We critically examine possible causes and focus on electron-lattice coupling mechanisms that are active at room temperature, and can lead to carrier scattering. From this, we propose scattering due to acoustic phonons or polarons as possible causes, but also point out the difficulties with each of these in view of additional experimental and theoretical findings in the literature. Further research in this direction will contribute to making HOIP solar cells even more efficient than they already are.