A novel nanowire array structure for photocurrent enhancement in amorphous silicon solar cell

Global warming and energy shortage are mankind´s greatest challenge in the recent years. The solution to this urgent crisis lies in replacing fossil fuel with renewable energy. One of the most attractive types of renewable energy is solar cell technology, and it is already being deployed around the world. Among many type of solar cells, thin film amorphous silicon (a-Si) solar cell is one of the candidate to achieve low cost requirement. In thin film a-Si solar cell, large amount gap states limit the use of thick film to absorb most of incident light that limit the efficiency. A novel cell structure in order to separate the way of light absorption and carrier transport was discussed in this work. Brendan et. al. first suggest this principle and simulate the electrical properties of planar and radial p-n nanorod solar cell with different materials like Si and GaAs. However, for a-Si solar cell, a built-in electrical that cause drift force for carriers was not involved in their work. In this work, the thin film solar cell with amorphous silicon p-i-n layers grown on ZnO: Al nanowire array was simulated. In this simulation, the diameter of the nanowire as small as 10 nm was used to fully utilize the advantage of nanowire structure. The physical models such as Poisson equation, drift-diffusion current equation and continuity equation are used. In addition to those physical equations, some parameters that associated to amorphous silicon are also used to construct the simulation environment in a commercial TCAD software.