The use of diethylselenide as a less-hazardous source in CuInGaSe2 photoabsorbing alloy formation by selenization of metal precursors premixed with Se

Selenization growth of phase-separation-free polycrystalline CuIn1–xGaxSe2(0⩽x⩽0.29)(0⩽x⩽0.29) films was demonstrated using a less-hazardous organometallic Se source, diethylselenide [(C2H5)2Se: DESe], and stacked structure of Se-premixed Cu–In–Ga metals called ‘precursors’. Distinct from the case of using Se vapor or H2Se gas, single-phase CuInGaSe2 films were obtained without thermal annealing using a combination of DESe and Se-premixed precursors. Photoluminescence spectra of the films at 77 K were dominated by the defect-related donor–acceptor pair and free electron to acceptor recombination emissions, which are particular to the CuInGaSe2 films exhibiting high-conversion efficiency.