Cr incorporation in CuGaS2 chalcopyrite: A new intermediate-band photovoltaic material with wide-spectrum solar absorption

An intermediate-band (IB) semiconductor CuGa1-xCrxS2 was investigated by the self-consistent many-body GW approach (scGW) and further confirmed by the experimental results. The Cr dopant introduced a partially occupied IB, and the density-of-states analysis indicates the electron transfer between the impurities and host lattice would suppress the non-radiative recombination. The CuGa1-xCrxS2 was synthesized by a high-temperature solid-state reaction and the X-ray photoelectron spectroscopy (XPS) indicated the presence of Cr3+. Due to the Cr dopant, two additional absorption responses were directly observed in the UV-Vis-NIR absorption spectrum. The further photocatalytic investigations verified the IB absorptions could produce highly mobile electrons and holes to degrade dyes. This material leads to lower-energy photon absorption, which could be a promising candidate for the high-efficiency solar cells.