Electrical Tunability of Quantum-Dot-in-Perovskite Solids

The quantum-dot-in-perovskite matrix (DIM) is an emerging class of semiconductors for optoelectronics enabled by their complementary charge transport properties and stability improvements. However, a detailed understanding of the pure electrical properties in DIM is still in its early stage. Here, we developed PbS quantum dot-in-CsSnI3 matrix solids exhibiting improved electrical properties and enhanced stability. PbS incorporation reduces the tensile strain of DIM films compared to that of pristine CsSnI3, consequently increasing the electrical conductivity. Electrical conductivity is tunable between 20 and 130 S/cm as a function of PbS concentration. Notably, a decoupling of electrical conductivity and Seebeck coefficient is observed upon PbS addition into the perovskite matrix, which is attractive for thermoelectric applications. Density functional theory analysis reveals that at low concentrations of PbS, light holes/electrons govern the overall transport properties in DIM, while heavy holes/electrons begin to dominate as the PbS concentration increases. Understanding the electrical properties would help for designing DIMs with specific properties for various technological applications.