Decoupling Bimolecular Recombination Mechanisms in Perovskite Thin Films Using Photoluminescence Quantum Yield

TL;DR

This paper introduces a new analytical model to analyze the spectral photoluminescence quantum yield of perovskite thin films, enabling decoupling of various recombination mechanisms without multiple measurements.

Contribution

The novel model simplifies the analysis of recombination processes in semiconductor thin films by avoiding complex experimental procedures and providing consistent, validated results.

Findings

Validated model aligns with established methods.

Accurately decouples radiative and non-radiative recombination.

Predicts efficiency losses from recombination mechanisms.

Abstract

We present a novel analytical model for analysing the spectral photoluminescence quantum yield of non-planar semiconductor thin films. This model considers the escape probability of luminescence and is applied to triple-cation perovskite thin films with a 1-Sun photoluminescence quantum yield approaching 25%. By using our model, we can decouple the internal radiative, external radiative, and non-radiative bi-molecular recombination coefficients. Unlike other techniques that measure these coefficients separately, our proposed method circumvents experimental uncertainties by avoiding the need for multiple photoluminescence measurement techniques. We validate our model by comparing the extracted implied open-circuit voltage, effective luminescence escape probabilities, absorptivity, and absorption coefficient with values obtained using established methods and found that our results are consistent with previous findings. Next, we compare the implied 1-Sun radiative open-circuit voltage and radiative recombination current obtained from our method with literature values. We then convert the implied open-circuit voltage and implied radiative open-circuit voltage to the injection-dependent apparent-effective and apparent-radiative carrier lifetimes, which allow us to decouple the different recombination coefficients. Using this lifetime analysis, we predict the efficiency losses due to each recombination mechanism. Our proposed analytical model provides a reliable method for analysing the spectral photoluminescence quantum yield of semiconductor thin films, which will facilitate further research into the photovoltaic properties of these materials.