Perovskite solar cells dominated by bimolecular recombination -- how far is the radiative limit?

TL;DR

This study demonstrates that perovskite solar cells are limited by bimolecular recombination and introduces new characterization methods to analyze their performance relative to radiative limits, offering insights for efficiency improvements.

Contribution

The paper provides a comprehensive experimental and analytical framework to assess bimolecular recombination limits in perovskite solar cells, aligning their performance with radiative efficiency benchmarks.

Findings

Perovskite solar cells operate at bimolecular recombination limits.

New characterization schemes enable extraction of recombination parameters.

Recombination parameters predict dark J-V and Suns-V_OC features.

Abstract

Here, we report an experimental demonstration of perovskite solar cells dominated by bimolecular recombination and critically analyse their performance against radiative limits. To this end, we first establish a set of quantitative benchmark characteristics expected from solar cells limited by bimolecular recombination. Transient as well as steady state intensity dependent measurements indicate that our solar cells indeed operate at such limits with interface passivation comparable to the champion c-Si technology. Further, we identify novel characterization schemes which enable consistent back extraction of recombination parameters from transient optoelectrical and electroluminescence measurements. Remarkably, these parameters predict important features of dark current density vs. voltage characteristics (J-V) and Suns-V_OC measurements, thus validating the estimates and the methodology. Uniquely, this work provides a consistent and coherent interpretation of diverse experimental trends ranging from dark J-V, Suns-V_OC, steady state and transient intensity dependent measurements to electroluminescence quantum yield. As such, insights shared in this manuscript could have significant implications towards fundamental electronic processes in perovskite solar cells and further efficiency optimization towards Shockley-Queisser limits.