Insulator-to-metal transition in intermediate-band materials: insights from temperature-dependent transmission computations

Abstract

Insulator-to-metal (I–M) transition is crucial for an intermediate-band (IB) photovoltaic material to suppress the non-radiative recombinations and improve its efficiency. Nevertheless, the mechanism and critical condition of the I–M transition is not clear yet. In this work, the critical conditions of the I–M transition in two types of Si-based IB materials were studied by combining the molecular dynamics simulations and Landauer transmission calculations. It shows that the I–M transition of the substitutional configuration of S will occur when the filled IB is expanded and merged with the conduction band, which fulfills the Mott transition theory. But this type of IB material is not a standard IB material proposed by Luque. For the substitutional configuration of N, which can be regarded as a standard IB material, the I–M transition would be occurred when the partially-filled IB is expanded and the localization of the carriers in the IB is weakened. The metallic state of the IB material is different from typical metals and they still exhibit some semiconductor properties at low temperature.

Keywords

• insulator-to-metal transition
• intermediate-band
• electronic transmission
• conductivity
• nonequilibrium Green’s function