Novel patterning of CdS / CdTe thin film with back contacts for photovoltaic application

The heterostructure of patterned CdS / CdTe thin films with back contact have been devised with electron beam lithography and fabricated using sputter deposition technique. The metallic contacts for n-CdS and p-CdTe are patterned such that both are placed at the bottom of the cell. This avoids losses due to contact shading and increases absorption in the window layer. Patterning of the device surface helps in increasing the junction area which can modulate the absorption of more number of photons due to total internal reflection. Computing the surface area between a planar and a patterned device has revealed 133% increase in the junction area. The physical and optical properties of the sputter-deposited CdS / CdTe layers are also presented. J–V characteristics of the solar cell showed the fill factor to be 25.9%, open circuit voltage to be 17 mV and short-circuit current density to be 113.68A/m2. The increase in surface area is directly related to the increase in the short circuit current of the photovoltaic cell, which is observed from the results of simulated model in Atlas / Silvaco.