A highly efficient nano-graphite electron transport layer for high performance ZnO/Si solar cells

Photovoltaic modules are considered as the most efficient way to utilize solar energy, while the power conversion efficiencies of commercial crystalline silicon (c-Si) solar cells still need to be improved. Herein, nano-graphite was designed as a highly efficient electron transport layer in high performance ZnO/Si solar cells and prepared via a simple solution phase deposition and rapid annealing process. The ZnO QDs can broaden the range of spectral response by generating more electron–hole pairs via multiple exciton effects. The built-in-field formed between the n-type ZnO QD layer and n-type Si and highly conductive nano-graphite can accelerate the electron collection and transportation from n-type Si to the front electrode. Thus, the designed Si solar cell with nano-graphite and ZnO QD layers shows a significantly improved power conversion efficiency of 14.99% compared to the ZnO/Si solar cell (13.62%) and unmodified commercial c-Si solar cells (12.73%). This cost effective and environmentally friendly technology can be easily applied for the industrial scale production of Si solar cells.