Unveiling high-mobility hot carriers in a two-dimensional conjugated coordination polymer
Shuai Fu, Xing Huang, Guoquan Gao, Petko St. Petkov, Wenpei Gao, Jianjun Zhang, Lei Gao, Heng Zhang, Min Liu, Mike Hambsch, Wenjie Zhang, Jiaxu Zhang, Keming Li, Ute Kaiser, S. Parkin, Stefan C. B. Mannsfeld, Tong Zhu, Hai I. Wang, Zhiyong Wang, Renhao Dong⧫, Xinliang Feng, Mischa Bonn
Abstract
Abstract Hot carriers, inheriting excess kinetic energy from high-energy photons, drive numerous optoelectronic applications reliant on non-equilibrium transport processes. Although extensively studied in inorganic materials, their potential in organic-based systems remains largely unexplored. Here we demonstrate highly mobile hot carriers in crystalline two-dimensional conjugated coordination polymer Cu 3 BHT (BHT, benzenehexathiol) films. Leveraging a suite of ultrafast spectroscopic and imaging techniques, we map the microscopic charge transport landscape in Cu 3 BHT films following non-equilibrium photoexcitation across temporal, spatial and frequency domains, revealing two distinct high-mobility transport regimes. In the non-equilibrium regime, hot carriers achieve an ultrahigh mobility of ~2,000 cm 2 V –1 s –1 , traversing grain boundaries up to ~300 nm within a picosecond. In the quasi-equilibrium regime, free carriers exhibit Drude-type, band-like transport with a remarkable mobility of ~400 cm 2 V –1 s –1 and an intrinsic diffusion length exceeding 1 μm. These findings position two-dimensional conjugated coordination polymers as versatile platforms for advancing organic-based hot carrier applications.