The first practical use of lead acetate as a precursor in generating formamidinium-cesium perovskite solar cells has established a new avenue to developing durable, efficient perovskite photovoltaics at industrial scale.
Exciton Science, located at Monash University, created perovskite solar cells with a 21% efficiency, the highest yet reported for a device manufactured from a non-halide lead source.
The efficiency of a tiny prototype solar panel made up of these cells was 18.8%. The large-area perovskite layer was created in an ambient environment via a single-step blade coating, proving its potential for industrial-scale production.
The test devices also demonstrated excellent thermal stability, with no efficiency loss after 3,300 hours of operation at 65°C.
“We were able to employ lead acetate in a one-step, spin-coating procedure to achieve the ideal, high-quality formamidinium-cesium perovskite thin film,” stated first author Jie Zhao, a Ph.D. student at Monash University.
“And since we don’t require an anti-solvent ingredient, we can achieve this using large-scale processes like blade coating, which means it’s industrially practical.”
The findings were published in the journal Energy and Environmental Science.
“The great bulk of perovskite solar cell research involves lead halides, notably lead iodide,” stated corresponding author and Monash University colleague Dr. Wenxin Mao.
“The lead iodide has to be 99.99% pure and it’s highly costly to create cells using lead iodide.
“We’re the first group to develop very stable formamidinium-cesium perovskite solar cells utilising lead acetate rather than lead iodide. We have given the whole scientific community a second method for producing high-quality perovskite solar cells.”
More on perovskites: benefits against drawbacks
Thin film solar cells built of perovskites have the potential to disrupt the solar energy business due to its cheap production cost, flexibility, and customizable band gap in comparison to silicon. However, researchers are striving to tackle reliability difficulties, and they must also discover a means to produce devices on a commercially feasible scale.
Perovskites are solution processed (produced in liquid) from a range of components. To manage the perovskite crystallisation process, most ways employ lead halides and need the addition of strong polar solvents with high boiling temperatures and antisolvent quenching agents. This complex operation may generate faults in the thin layers, causing the resultant device to lose efficiency quickly. It’s also difficult to regulate.
Because it can produce ultrasmooth thin films with fewer flaws, the chemical compound lead acetate has emerged as a possible alternative precursor. Lead acetate was previously exclusively utilised to create methylammonium or cesium-based perovskites, which are rather unstable and unsuitable for real-world applications.
Because of their improved stability, perovskites produced from formamidinium and cesium are a better choice for commercial usage. Attempts to manufacture them before using lead acetate as a precursor failed. To understand and fix this problem, the researchers studied the underlying molecular pathways alongside partners from Wuhan University of Technology in China. They discovered the necessity for ammonium as a volatile cation (positively charged ion) at a key stage using X-ray diffraction and nuclear magnetic resonance spectroscopy.
“The presence of ammonium helped to drive away the leftover acetate during annealing, without producing undesirable side products,” explained co-author Dr. Sebastian Fürer.
The researchers expect that their work on the underlying chemistry that governs precursor behaviour will lead to a greater emphasis on scalable synthesis and manufacturing approaches for metal halide perovskite devices.
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