Ultrafast, light-induced dynamics in copper–zinc–tin–sulfide (CZTS) photovoltaic nanoparticles are investigated through a combination of optical and x-ray transient absorption spectroscopy. Laser-pump, x-ray-probe spectroscopy on a colloidal CZTS nanoparticle ink yields element-specificity, which reveals a rapid photo-induced shift of electron density away from Cu-sites, affecting the molecular orbital occupation and structure of CZTS. We observe the formation of a stable charge-separated and thermally excited structure, which persists for nanoseconds and involves an increased charge density at the Zn sites. Combined with density functional theory calculations, the results provide new insight into the structural and electronic dynamics of CZTS absorbers for solar cells.

中文翻译：

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溶液中光激发的Cu2ZnSnS4纳米粒子超快动力学的元素特定研究

通过结合光学和X射线瞬态吸收光谱研究了铜-锌-锡-硫化物（CZTS）光伏纳米粒子中的超快光诱导动力学。胶体CZTS纳米粒子墨水上的激光泵浦，x射线探针光谱学可得出元素特异性，这揭示了光密度引起的电子密度从Cu位置快速移出，影响了CZTS的分子轨道占据和结构。我们观察到形成了稳定的电荷分离和热激发结构，该结构持续了纳秒，并且涉及到锌位点上增加的电荷密度。结合密度泛函理论计算，结果为太阳能电池CZTS吸收剂的结构和电子动力学提供了新的见识。