Discerning Rise Time Constants to Quantify Charge Carrier Extraction in Perovskite Solar Cells
Sandheep Ravishankar a
a Forschungszentrum Jülich, Institute of Energy and Climate Research, IEK-5 Photovoltaics, Wilhelm-Johnen-Straße, Jülich, Germany
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)
València, Spain, 2024 May 12th - 15th
Organizer: Bruno Ehrler
Oral, Sandheep Ravishankar, presentation 015
DOI: https://doi.org/10.29363/nanoge.hopv.2024.015
Publication date: 6th February 2024

The small-perturbation analysis of perovskite solar cells (PSCs) highlights a fundamental conundrum – while time domain measurements yield two time constants corresponding to the rise and subsequent decay of the photovoltage or photocurrent, the corresponding frequency domain methods only yield one time constant from the analysis of the negative imaginary part of the transfer function. To solve this problem, we propose a modification of the frequency domain transfer function that focusses on the transition of its real part to negative values at high frequencies. After verification using drift-diffusion simulations and equivalent circuit analysis, the application of the method to experimental intensity-modulated photovoltage spectroscopy data of a PSC allows calculation of the hidden rise time constant, showing a good agreement with rise time constants obtained from transient photovoltage measurements. Combining these measurements with transient photoluminescence measurements allows calculation of the figure of merit (FOM) that determines the charge collection efficiency. We determine large FOM values between 0.7–0.95 at or close to the 1 sun open-circuit voltage, indicating a significant electric field exists in the transport layers that allows fast charge collection in these conditions.

This work was supported by the Deutsche Forschungsgemeinschaft (DFG) through a Walter-Benjamin fellowship – project number 462572437, the Helmholtz association via the POF IV, the innovation platform SolarTap and the project ‘Beschleunigter Transfer der nächsten Generation von Solarzellen in die Massenfertigung - Zukunftstechnologie Tandem-Solarzellen’, Forschungszentrum Jülich via the HITEC graduate school.

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