Harvesting Plasmonic Near-Infrared Photons by Hot Hole Transfer in Nonstoichiometric-Semiconductor Plasmonic Heterojunctions

Infrared light is an untapped energy source that accounts for half of solar energy. Thus, harvesting near-infrared photons for different applications needs further development for efficient utilization of the whole solar spectrum. Herein, we report harvesting infrared photons by hot hole transfer from a nonstoichiometric plasmonic semiconductor (Cu2-xSe) to an adjacent semiconductor (CdSe) in the heterostructure (HNCs). We found a decrease in transient signal intensity and hole-phonon scattering time in Cu2-xSe/CdSe HNCs compared to the pure Cu2-xSe nanocrystals, attributed to plasmon-induced hot hole transfer. A similar kind of TA kinetics has been observed for 800 and 930 nm laser pulse excitation for Cu2-xSe/CdSe HNCs. The spectroscopic results reveal anomalous carrier populations and slow carrier recovery dynamics at the 1P state of the CdSe phase in Cu2-xSe/CdSe HNCs, further establishing the plasmonic hot hole transfer mechanism. The estimated plasmon-induced hot hole transfer time from the nonstoichiometric semiconductor Cu2-xSe NC system is determined and found to be similar to 177 fs. Fabricated plasmonic thin-film devices exhibit an excellent conductivity (0.15 A at 2 V) and photoconductivity (0.2 A at 2 V) under near-infrared light illustration (Alight = 1200 nm) in a plasmonic HNC system. These results reveal a novel approach for harvesting light photons from the visible to near-infrared region of the solar spectrum and provide a new avenue for developing hot carrier-based device applications of plasmonic semiconductor-based nanomaterials.