Cesium Lead Inorganic Solar Cell with Efficiency beyond 18% via Reduced Charge Recombination.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Cesium-based inorganic perovskite solar cells (PSCs) show promise for enhanced device stability.
• Low power conversion efficiency in inorganic PSCs, compared to hybrid PSCs, is attributed to open-circuit voltage (VOC) loss from charge recombination.
• Addressing these limitations is crucial for advancing perovskite solar technology.

Purpose of the Study:

• To improve the efficiency and stability of cesium-based inorganic perovskite solar cells.
• To mitigate charge recombination losses and enhance energy level alignment.
• To investigate the impact of interface engineering and precursor modification on device performance.

Main Methods:

• Incorporation of a lithium fluoride (LiF) insulating shunt-blocking layer on the SnO2 electron transport layer.
• Passivation of interface defects and improved energy level alignment between SnO2 and CsPbI3-xBrix.
• Addition of lead chloride (PbCl2) to the CsPbI3-xBrix precursor to enhance film crystallinity and suppress recombination.

Main Results:

• Optimized CsPbI3-xBrix PSCs with a 1.77 eV band gap achieved a maximum VOC of 1.25 V and a power conversion efficiency of 18.64%.
• Significant enhancement in perovskite film crystallinity and suppression of charge recombination were observed.
• High photostability was demonstrated, with less than a 6% efficiency drop after 1000 hours of continuous illumination.

Conclusions:

• The strategic use of LiF as a shunt-blocking layer and PbCl2 in the precursor effectively addresses key challenges in inorganic PSCs.
• These advancements lead to substantial improvements in both efficiency and operational stability.
• The developed CsPbI3-xBrix PSCs represent a significant step towards stable and efficient perovskite solar technology.