Uncovering the mechanisms of efficient upconversion in two-dimensional perovskites with anti-Stokes shift up to 220 meV

作者：Bo Wu, Aocheng Wang, Jing Fu, Yutong Zhang, Cheng Yang, Yiyang Gong, Chuanxiu Jiang, Mingzhu Long, Guofu Zhou, Shuai Yue, Wei Ma, Xinfeng Liu · 发表于：Science Advances · 年份：2023 · DOI：10.1126/sciadv.adi9347 · 被引用次数：55 · 研究领域：Optical properties and cooling technologies in crystalline materials、Perovskite Materials and Applications、Thermal Radiation and Cooling Technologies

Phonon-assisted photon upconversion holds great potential for numerous applications, e.g., optical refrigeration. However, traditional semiconductors face energy gain limitations due to thermal energy, typically achieving only ~25 milli-electron volts at room temperature. Here, we demonstrate that quasi-two-dimensional perovskites, with a soft hybrid organic-inorganic lattice, can efficiently upconvert photons with an anti-Stokes shift exceeding 200 milli-electron volts. By using microscopic transient absorption measurements and density functional theory calculations, we explicate that the giant energy gain stems from strong lattice fluctuation leading to a picosecond timescale transient band energy renormalization with a large energy variation of around ±180 milli-electron volts at room temperature. The motion of organic molecules drives the deformation of inorganic framework, providing energy and local states necessary for efficient upconversion within a time constant of around 1 ps. These results establish a deep understanding of perovskite-based photon upconversion and offer previously unknown insights into the development of various upconversion applications.