Photoelectrochemical cells based on ternary compounds CuIn2n + 1Se3n + 2 (n = 3–6)

Single crystals of ternary CuIn2n + 1Se3n + 2 semiconductors with the composition index n = 3, 5, 6 were grown for the first time using the direct crystallization method. It was shown that these crystals have hexagonal symmetry and close unit cell parameters. Photoelectrochemical cells based on CuIn2n + 1Se3n + 2 and In2Se3 single crystals were fabricated. Their photosensitivity spectra were measured for the first time, which were used to determine the nature of interband transitions and the band gap. The weak dependence of the parameters of the band’s spectrum and unit cell of these semiconductors at n ≥ 2 was attributed to the features of the interatomic interaction in such phases. It was concluded that new CuIn2n + 1Se3n + 2 semiconductors can be used in broadband photoconverters of optical radiations.