One-Dimensional Perovskite-like Cu(I)-Halides with Ideal Bandgap Based on Quantum-Well Structure

Low-dimensional halide perovskites with quantum-well structures are promising materials for electronics and optoelectronics because of their excellent optoelectronic properties. This work concerns two novel, lead-free, one-dimensional organic-inorganic hybrid perovskite-like Cu(I) halides, (MV)Cu2X4 (MV = methyl viologen; X = Br, I), for optoelectronic applications. Both Cu(I) halides exhibited good stability under ambient conditions. The optical bandgaps of (MV)Cu2Br4 and (MV)Cu2I4 are 1.4 and 1.5 eV, respectively, which are in the ideal bandgap range for solar cells. (MV)Cu2Br4 possessed a characteristic quantum-well structure in which [CuBr4]n3n- chains with a nanowire-like structure were rolled up and isolated by tightly packed organic cations. Thanks to quantum confinement in the unique structure, the optical bandgap of (MV)Cu2Br4 fell in the ideal bandgap range for solar cells and was superior to that of (MV)Cu2I4. The good photoresponse properties of these Cu(I) halides suggest their great potential for application as light-harvesting materials in solar cells.