Ligand size effects in two-dimensional hybrid copper halide perovskites crystals
Arramel Arramel, Angga Dito Fauzi, Xinmao Yin, Chi Sin Tang, Muhammad Haris Mahyuddin, Muhammad Fauzi Sahdan, Mimin Aminah, Djulia Onggo, Ganes Shukri, Caozheng Diao, Hong Wang, Muhammad Danang Birowosuto, Andrew T. S. Wee, Andrivo Rusydi
Abstract
Abstract Intensive effort to tailor photophysics of lead-free perovskites is appealing in recent years. However, their combined electronic and optical property elucidations remain elusive. Here, we report spectroscopic observations of the coexistence Zhang-Rice singlet state and exotic electronic transitions in two-dimensional copper-based perovskites. Herein, several perovskites with different alkylammonium spacers are investigated to unravel their correlated electronic systems and optical responses. Namely, methylammonium, ethylammonium, phenylmethylammonium and phenethylammonium. Using temperature dependent high-resolution X-ray absorption spectroscopy, we observe distinct electronic features highlighting the impact of short spacer chains compared to long-conjugated ligands, demonstrating a pronounced 3 d 9 and 3 d 9 L signature linewidth variation. Corroborated by density functional theory calculations, the transient dynamics evolution of copper-based hybrid perovskites is influenced by the strong interplay of electron-phonon interactions and geometric constrictions. This finding sheds light on tuning the electronic and optical properties of hybrid perovskites towards efficient photoactive-based devices.