Analytical study of carrier photogeneration and photocurrent in thin silicon solar cells with specular and diffuse back reflection

An analytical study of the effect of back reflection in thin silicon solar cells implementing a practical (nonideal) diffuse reflector at the back side is presented. Both the diffuse and specular reflection components are considered. The reflection properties of the back reflector are described by means of three parameters, which are interpreted in terms of a simple physical model. An exact expression for the generation profile resulting from specular and diffuse reflections is derived and its dependence on the reflector parameters is studied. A mechanism through which specular reflection can significantly enhance light trapping in the case of relatively weak diffuse reflection is proposed. The photocurrent boost doe to both types of reflections acting simultaneously is estimated.