Diamond Thin Films for PV Solar Cells on the Base of a-SiC:H Alloy

Abstract

Thin-film photovoltaic (PV) cells based on a-Si:H have been and still are optimized. In this work, we present PV cells based on a-SiC:H alloys with low carbon content [1] deposited (compared to PV cells based only on a-Si:H) at elevated temperatures. The increased deposition temperature is in line with the deposition temperatures for consequent diamond layer deposition and helps to stabilize the achieved energy conversion efficiency. Thin diamond layers act as optically transparent material with a wide bandgap (5.47 eV) and a high optical refractive index (2.41). The outstanding properties of diamond are high chemical resistance, high mechanical hardness, and high thermal conductivity. Technological processes make it possible to diverge diamond from nanocrystalline to microcrystalline layers. The diamond crystal size governs the efficiency of the scattering of the incident light and its increased absorption in the connected structure of the PV cell. Both of these properties - high thermal conductivity and optimized layer roughness - are excellent prerequisites for the new structuring of thin-film PV cells. By efficient heat dissipation, PV cells operate in a mode of lower temperatures and thus higher energy conversion efficiency, even in the systems loaded with highly concentrated solar energy.