A thin layer of Carbon Nano Tube (CNT) as semi-transparent charge collector that improve the performance of the GaAs Solar Cell

A novel use of carbon nanotube networks (CNT) as a semi-transparent layer for better charge collector in GaAs solar cells in order to improve the overall cell performance is presented. The different photovoltaic behaviors have been investigated considering substrate thickness, cell width, dependence between CNT work function and transmittance. CNT layer thickness is found to be optimized at 100 nm for AM1.5G. The sheet resistivity is evaluated at 128 Ω/□. The performance parameters of a cell with and without the CNT network are compared. The CNT networks allow for a greater area of charge collection on the surface of solar cells as well as serve as a lower resistance path for charge carriers with minimum voltage loss to travel to the top contact. This model thus significantly improves the power conversion efficiency from 26.04% to 29.18% under AM1.5G. The addition of a CNT layer was shown to minimize the voltage drop and maintain high maximum power levels at 34.4 mW/cm2 for cells with larger width. EQE of the cell is well above 90%. The model has been validated with various reported experimental works. CNT layers with lower sheet resistance and better light transmission can therefore greatly improve the efficiency of solar cells.