Two-dimensional modelling and simulation of hydrogenated amorphous silicon p+–n–n+ solar cell

Abstract

Two-dimensional device modelling for hydrogenated amorphous silicon p + –n–n + solar cell has been carried out by using MEDICI ™ device simulator and the influence of absorber layer thickness, doping concentration, and dangling bond density of states in absorber layer on photo parameters are investigated. A strong correlation between n-type doping and dangling bond density in the absorber layer relative to the stability of the a -Si:H solar cell is observed. An increased stabilized efficiency is obtained when n-type dopant concentration in the absorber layer is higher than optimum value for higher initial efficiency. The window layer (p + layer) of the device is designed with a three layered structure of graded doping for higher device performance. This window layer structure in the a -Si:H p + –n–n + cell resulted in higher open circuit voltage and fill factor and hence higher efficiency of the cell. The efficiency of the modified amorphous silicon solar cell structure is found to be 12.85%.