What is it about?

Perovskite solar cells (PSCs) have high power conversion efficiencies (PCE), which contributes to their wide demand. Carbon electrodes used in PSCs lower the risk of corrosion. This has inspired the development of carbon electrode-based PSCs (CPSCs). The mesoscopic structure of CPSCs promises high PCE at low temperatures. The use of high-quality perovskite crystallites can improve their performance further. This can be determined by analyzing the crystallization of perovskite on the device surface. The authors of this study observed perovskite crystallization in low temperature meso CPSCs. They used film thickness of the carbon electrode and volume of the perovskite solution to track the changes. Their aim was to increase the PCE and make device fabrication more efficient. They show that this is possible by controlling the uneven crystallization of perovskite. This affects the device’s charge transfer and recombination.

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Why is it important?

Solar cells can solve the growing demand for clean energy, but they have low PCE and are costly to fabricate. This limits their widespread use. This study focused on improving these two factors. It targeted the uneven crystallization of perovskite on the device surface to achieve this goal. The samples with uneven crystallization had a low PCE, of about 3%. This was due to the slowed charge transfer and increased recombination risk. But the sample with uniform crystallization had a PCE of about 11%. Crystallization must be controlled to produce stable and effective low temperature meso CPSCs. KEY TAKEAWAY: Perovskite solar cells are the future of energy consumption. But preferred solvent evaporation on the device surface is a big challenge. Reducing uneven crystallization of meso CPSCs may increase the device's PCE. This can then help us fabricate efficient low temperature meso CPSCs.

Perspectives

Carbon-electrode based mesoporous perovskite solar cells (meso CPSCs) are known by the excellent stability. Understanding the crystallization dynamics of halide perovskite is quite essential for highly efficient device preparation. Different from conventional metal-electrode basing PSCs, perovskite crystallization in meso CPSCs relies on the four processes: infiltration of perovskite precursor in the triple layered porous skeleton, solvent evaporation, nucleation and growing up. Present work shows that, crystallization of perovskite crystallites on top of the skeleton (or out of the skeleton) could affect the crystallization in the skeleton. There exists competition between the two. This finding opens a door to explore the novel crystallization process, and will help to build more efficient and stable meso CPSCs, especially for the low temperature ones.

Prof. Conghua Zhou
Central South University

Read the Original

This page is a summary of: Uneven crystallization of lead halide perovskite in the carbon-electrode based, low-temperature mesoscopic perovskite solar cells, Journal of Applied Physics, November 2022, American Institute of Physics,
DOI: 10.1063/5.0120065.
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