Silicon cells, used in almost all commercial solar panels, are limited to converting a narrow frequency band of sunlight to electricity. The light that doesn't fall within this range is either transmitted through or lost as heat, thus limiting the theoretical efficiency of silicon cells to approximately 29.4%.
This efficiency ceiling could be theoretically surpassed by stacking another material, capable of generating electricity from a different frequency range of light, onto the silicon layer. Perovskite, a crystal composed of titanium and calcium, is a promising candidate due to its proficiency in absorbing light near the infrared spectrum. However, its efficiency has been challenging to enhance due to reabsorbed electrons that fail to convert into current.
Two research groups have made breakthroughs in pairing perovskite with silicon to achieve superior efficiency. By using a two-step process that involves coating the silicon cell with precursor chemicals and then adding a second layer of chemicals to form perovskite, Xin-Yu Chin at the Swiss Federal Institute of Technology Lausanne and his team achieved an efficiency of 31.2%.
In a separate research, Silvia Mariotti and her team at Helmholtz-Zentrum Berlin injected liquid piperazinium iodide into the perovskite layer to reduce the number of wandering electrons, achieving an impressive 32.5% efficiency rate.
Although these efficiency rates are currently applicable to solar cells smaller than those required for commercial use, Oxford PV, a solar firm, demonstrated in May that perovskite-silicon tandem cells could be manufactured at a production-ready scale, albeit at a slightly reduced efficiency level of 28%.
Stability over a long period is a concern, but if large-scale production is viable as some companies have demonstrated, the future of solar energy looks bright.
Journal reference:
ScienceDOI: 10.1126/science.adg0091
Journal reference:
ScienceDOI: 10.1126/science.adf5872
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