Effect of the structure of lead iodine perovskites on the photovoltaic efficiencies

TL;DR

This study investigates how the microscopic structural variations of methyl-ammonium lead iodide perovskites influence their optical absorption and photovoltaic efficiency, using first-principles calculations to quantify atomic contributions.

Contribution

It introduces a multi-species expansion methodology to analyze atomic contributions to absorption and efficiency in different perovskite phases, considering cell thickness effects.

Findings

Atomic contributions to absorption coefficients vary across structures.

Efficiency contributions from different atoms are quantifiable.

Cell thickness significantly impacts photovoltaic performance.

Abstract

Methyl-ammonium lead iodide perovskite crystallizes in different structures depending on the temperature: orthorhombic, tetragonal and cubic. An important point to be considered is the effect of the microscopic properties of the different structures on the optical and photovoltaic properties. Using first principles we obtain the absorption coefficients that will determine the absorption of solar radiation. In order to analyze the contributions of the different atoms to the absorption coefficients we split them into a many-species expansion. Using a similar methodology we also split the efficiencies as a many-species expansion. It allows the contribution of the atomic species to be identified and quantified to the absorption coefficients and to the solar cell efficiency of the different phases. Additionally the effect of the cell thickness w is quantified.