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Voltage-Dependent Photoluminescence and How It Correlates with the Fill Factor and Open-Circuit Voltage in Perovskite Solar Cells

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journal contribution
posted on 08.11.2019, 18:39 by Martin Stolterfoht, Vincent M. Le Corre, Markus Feuerstein, Pietro Caprioglio, L. Jan Anton Koster, Dieter Neher
Optimizing the photoluminescence (PL) yield of a solar cell has long been recognized as a key principle to maximize the power conversion efficiency. While PL measurements are routinely applied to perovskite films and solar cells under open-circuit conditions (VOC), it remains unclear how the emission depends on the applied voltage. Here, we performed PL­(V) measurements on perovskite cells with different hole transport layer thicknesses and doping concentrations, resulting in remarkably different fill factors (FFs). The results reveal that PL­(V) mirrors the current–voltage (JV) characteristics in the power-generating regime, which highlights an interesting correlation between radiative and nonradiative recombination losses. In particular, high FF devices show a rapid quenching of PL­(V) from open-circuit to the maximum power point. We conclude that, while the PL has to be maximized at VOC, at lower biases < VOC, the PL must be rapidly quenched as charges need to be extracted prior to recombination.