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Breakthrough in tin-based perovskite solar cells achieves 11 percent power conversion efficiency



In the rapidly evolving field of solar energy, tin perovskite solar cells have emerged as a significant area of interest, particularly for their potential in creating lead-free alternatives. A recent development from the Nanjing University of Posts and Telecommunications, led by Prof. Ligang Xu, has marked a notable advancement in this sector.


Their research, focusing on overcoming the challenges of deep-level traps in tin perovskite solar cells, has been highlighted in their paper, "Suppression of deep-level traps via semicarbazide hydrochloride additives for high-performance tin-based perovskite solar cells," published on December 29, 2023, in Frontiers of Optoelectronics.


Deep-level traps in tin perovskite solar cells, predominantly caused by Sn vacancies and undercoordinated Sn ions, have been a persistent issue. These traps lead to non-radiative recombination and the absorption of nucleophilic O2 molecules, both of which significantly impede the efficiency and stability of these devices.


Addressing this challenge, the research introduces a novel method - the integration of semicarbazide hydrochloride (SEM-HCl) into the tin perovskite precursor. This technique has been instrumental in fabricating high-quality perovskite films with a markedly low concentration of deep-level traps.


The SEM-HCl plays a dual role in enhancing the quality of tin perovskite films. Firstly, it diminishes the quantity of uncoordinated Sn2+ ions on the surface, and secondly, it modulates the intrinsic Sn deep-level defects. This comprehensive modulation is key to enhancing device performance.


The O=C-N functional group in SEM-HCl forms coordination interactions with charge defects of the tin perovskites. This interaction intensifies the electron cloud density surrounding the defects, thereby enlarging vacancy formation energies. This approach is crucial in reducing the deep-level trap state density, which originates from undercoordinated Sn2+ ions and Sn4+ oxidation.


By effectively reducing nonradiative recombination and extending the charge lifetime, the tin-based perovskite solar cells (TPSCs) achieve a champion power conversion efficiency (PCE) approaching 11%, a significant stride in the realm of solar cell technology.


An equally impressive feat is the stability of these newly developed cells. The unencapsulated devices maintained almost 100% of their initial efficiencies after operating for 100 hours under AM1.5 illumination conditions. This level of stability, coupled with the improved efficiency, marks a significant step forward in the practical application of tin-based perovskite solar cells.


Prof. Ligang Xu's team has effectively addressed one of the major hurdles in the development of efficient and stable tin perovskite solar cells. By employing SEM-HCl, they have not only improved the performance of these cells but also opened new avenues for further research and development in lead-free perovskite solar cells. This advancement aligns well with the global shift towards sustainable and environmentally friendly energy solutions, offering a promising future for solar technology.


The implications of this research extend beyond the academic realm into the commercial and environmental sectors. With increasing concern over the use of lead in perovskite solar cells, the development of efficient lead-free alternatives is crucial. The approach demonstrated by Prof. Ligang Xu and his team represents a significant step in this direction, potentially paving the way for more widespread adoption of solar energy as a clean and renewable resource.