Technology Computer-Aided Design device simulation of nanowall-based CdS/CdTe solar cell for energy conversion

An innovative and novel electrode design for a Nanowall (NW)-based solar cell has been proposed and demonstrated previously. In this work, this concept has been implemented utilizing Technology Computer-Aided Design (TCAD) software SILVACO in NW-based n-CdS/ p-CdTe solar cell to illustrate its potential for NW-based solar cell technology. The device's photovoltaic parameters have been investigated as a function of geometrical factors like NW height and CdS window layer thickness, as well as parameters like mid-gap and interface defects. The influence of the increase in the NW height seems to be increasing the photovoltaic parameters such as short circuit current density (J(sc)), fill factor (FF), and power conversion efficiency (Eff) of the device. Increasing the depth of the CdS window layer has shown a slight decrease in the photovoltaic parameters. Besides, the effect of the defect density mid-gap acceptor-like states in the CdS layer and at the interface has also been simulated. It has been found that by increasing the mid-gap defect states, a drop of 38, 18, and 45% in J(sc), FF, and Eff respectively has been observed with a very small rise of 4% in Voc. It has also been observed that increasing the defect states causes not only a decrease in J(sc), FF, and Eff, but also an increase in blue loss in the lower wavelength range. Moreover, mid-gap defect states seem to degrade the photovoltaic parameters much more severely than the interface defect states at the nanoscale dimension.