Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells

Two-dimensional nanomaterials (2DNs) due to their broadband absorption (graphene) and high absorption coefficient (MoS2 or WS2) are attractive for optoelectronics including solar cells. Recent advances in 2DNs-based photovoltaics is based on interfacing 2DNs with conventional bulk 3D semiconductors to build a new class of 2D/3D heterojunction solar cells. Currently, such 2D/3D heterojunction solar cell devices are fabricated via mechanical/chemical transfer of 2D layers onto 3D bulk semiconductors, which poses challenges for large-scale integrations. In this project, transfer-free, large-area graphene/n-silicon (G/n-Si) heterojunction solar cells are developed via chemical vapor deposition (CVD). The directly-grown graphene films are characterized via combined spectroscopic (Raman and XPS) and microscopic (FESEM) techniques. Several CVD process optimizations have been made to understand the growth kinetics of graphene on n-Si surfaces. A power conversion efficiency of 1.3% is achieved for G/n-Si heterojunction solar cells with silver nanoparticles as plasmonics centers. Factors such as: structural quality, quantum opto-plasmonics affecting the performances of these new generation photovoltaics will be discussed.