研究目的
Investigating the reversible changes in perovskite solar cells (PSC) by electrochemical impedance spectroscopy (EIS) to understand the impact of ionic migration on device performance and stability.
研究成果
The study demonstrates that the high-frequency impedance of perovskite solar cells changes significantly over time due to continuous polarization at VOC under light, proposing a temporary loss of electronically active area as the main effect. This effect is reversible, suggesting that ionic migration results in decreased injection and increased recombination at the contacts. The findings highlight the importance of considering operating conditions in impedance analysis and suggest that the high-frequency semicircle can be used to monitor ionic migration in PSCs.
研究不足
The study focuses primarily on the high-frequency part of the impedance spectra, leaving the low-frequency part less explored. The reversibility of changes is demonstrated, but the exact mechanisms behind the temporary loss of active area and its relation to ionic migration require further investigation.
1：Experimental Design and Method Selection:
EIS measurements were conducted at open circuit voltage (VOC) under 1.5G white LED light to analyze the impedance response of PSC devices. The study focused on the high-frequency part of the impedance spectra to understand the reversible changes in device performance.
2：5G white LED light to analyze the impedance response of PSC devices. The study focused on the high-frequency part of the impedance spectra to understand the reversible changes in device performance.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: The study used state-of-the-art perovskite films with mixed cation and anion composition, fabricated from solutions with differing concentrations of lead iodide (PbI2). Devices were characterized before and after recovery in the dark.
3：2). Devices were characterized before and after recovery in the dark.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Solartron 1260 impedance analyzer, white LED light source, perovskite solar cells with SnO2 as the electron transport layer and spiro-OMeTAD as the hole transport layer.
4：Experimental Procedures and Operational Workflow:
Devices were kept under light until VOC stabilized, followed by EIS measurements. The VOC was readjusted if necessary, and the measurement series was repeated. Devices were then kept in the dark for recovery before repeating measurements.
5：Data Analysis Methods:
High-frequency semicircles of EIS spectra were fitted to a simple process-oriented equivalent circuit model (ECM) consisting of a series resistor and an RQ element. The Kramers-Kronig test was used to validate the spectra.
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