Effects of Recombination Order on Open-Circuit Voltage Decay Measurements of Organic and Perovskite Solar Cells

Non-geminate recombination, as one of the most relevant loss mechanisms in organic and perovskite solar cells, deserves special attention in research efforts to further increase device performance. It can be subdivided into first, second, and third order processes, which can be elucidated by the effects that they have on the time-dependent open-circuit voltage decay. In this study, analytical expressions for the open-circuit voltage decay exhibiting one of the aforementioned recombination mechanisms were derived. It was possible to support the analytical models with experimental examples of three different solar cells, each of them dominated either by first (PBDBT:CETIC-4F), second (PM6:Y6), or third (irradiated CH3NH3PbI3) order recombination. Furthermore, a simple approach to estimate the dominant recombination process was also introduced and tested on these examples. Moreover, limitations of the analytical models and the measurement technique itself were discussed.

Automated summary

This study focused on the importance and impact of non-geminate recombination in solar cells, deriving analytical expressions to understand its different processes. Experimental examples were used to support the analytical models, revealing the dominant recombination process in each case. Additionally, limitations of the analytical models and measurement techniques were discussed.