PbS quantum dot solids and quantum dot size gradient layers for photovoltaics

Quantum dot (QD) solids are promising materials for the development of optoelectronic devices, in particular solar cells. The efficiency of such devices depends strongly on the energetic disorder within QD solid due to QD size variance and matching the energy of the components. Here, we studied optical properties, such as absorption, luminescence, time resolved luminescence spectra, and electrical conductivity of QD solid layers made of PbS QDs of different sizes (2.9 nm, 4.1 nm and 5.1 nm) as well as QD solid layers with QD size gradient. We discussed the efficiency of energy and charge transfer in layers with QD size gradient by performing theoretical estimates of the appropriate parameters. Additionally, we fabricated photovoltaic solar cells based on the QD solids and investigated an influence the energy disorder on the conductivity and the efficiency of solar cells.