López Cibrán, Kavanagh Seán R, Benítez Pol, Saucedo Edgardo, Walsh Aron, Scanlon David O, Cazorla Claudio
Departament de Física, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain.
Barcelona Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, 08019 Barcelona, Spain.
ACS Energy Lett. 2025 Jun 30;10(7):3562-3569. doi: 10.1021/acsenergylett.5c01267. eCollection 2025 Jul 11.
Pnictogen chalcohalides (MChX) represent an emerging class of nontoxic photovoltaic absorbers, valued for their favorable synthesis conditions and optoelectronic properties. Despite their proposed defect tolerance, stemming from the antibonding nature of their valence and conduction bands, their experimentally reported power conversion efficiencies remain below 10%, far from the ideal Shockley-Queisser limit of 30%. Using advanced first-principles simulation methods, we uncover a complex point-defect landscape in MChX, exemplified by BiSeI. Previously overlooked chalcogen vacancies are identified as critical nonradiative charge-recombination centers, which exist in high concentrations and, although they exhibit modest capture coefficients, can reduce the maximum power conversion efficiency down to 24%. We argue that such detrimental effects can be mitigated by cation-poor synthesis conditions and strategic anion substitutions. This study not only identifies efficiency-limiting factors in MChX but also provides a roadmap for their improvement, paving the way for next-generation solution-processed chalcogenide photovoltaics.
氮族硫卤化物（MChX）是一类新兴的无毒光伏吸收剂，因其良好的合成条件和光电性能而受到重视。尽管它们因价带和导带的反键性质而具有所谓的缺陷容忍性，但其实验报道的功率转换效率仍低于10%，远未达到理想的肖克利-奎塞尔极限30%。使用先进的第一性原理模拟方法，我们揭示了MChX中复杂的点缺陷情况，以BiSeI为例。先前被忽视的硫族空位被确定为关键的非辐射电荷复合中心，它们以高浓度存在，尽管其俘获系数适中，但可将最大功率转换效率降低至24%。我们认为，通过贫阳离子合成条件和策略性阴离子取代可以减轻这种有害影响。这项研究不仅确定了MChX中的效率限制因素，还为其改进提供了路线图，为下一代溶液处理的硫族化物光伏器件铺平了道路。
