Substrate-free flexible thin film solar cells by graphene-mediated peel-off technology

Abstract

Flexible electronics are currently one of the most important developing trends, which is normally fabricated and supported on external flexible substrates. In this work, we experimentally realized a facile graphene-mediated peel-off technology for the substrate-free flexible hydrogenated amorphous silicon (a-Si:H) thin film solar cell. The a-Si:H solar cells were firstly grown on high thermal tolerance rigid SiO2/Si substrates with graphene interlayers and then were facilely peeled off from the graphene/SiO2/Si substrate with high fidelity. The density functional theory calculations verify the fact that sandwiching the graphene sheet weakens the interaction between the solar device and SiO2/Si substrate with a 61% exfoliation energy drop. Subsequently, a microstructured polyethylene terephthalate film was designed as the window layer of the substrate-free a-Si:H device to promote the broadband and omnidirectional enhanced performance of the flexible device, as well as the mechanical strength. Our proposed graphene-mediated peel-off process can be extended to fabricate other light weight electronics and optoelectronic devices (especially for devices needed to be obtained under high temperature) and can potentially be developed into large-scale manufacturing in the future as well.