Silicon nano network p–n sandwich solar cell

•A new concept of sandwich-structured single crystal silicon solar cell is tested.•A layer of 3D silicon nanonetwork is sandwiched in between the p–n junction.•The prototype cell exhibits the power conversion efficiency of 12.1%.

This article reports a prototype of a sandwich-structured solar cell. A thin layer of three dimensional Si nanofiber was created between the p-type and n-type layers in a single homojunction silicon cell. This nanofibre layer, which works as a “space region”, was synthesized using MHz ultrafast laser ablation at ambient conditions. The high surface area of the nanofibrous layer having a certain degree of porosity enhances the excitation (hole/electron) when compared to the traditional p–n junction. Characterization with a standard solar simulator revealed improved device efficiency. The highest open circuit voltage, short circuit current and the maximum solar cell efficiency obtained are 16.21 mA/cm2, 0.95 V, and 12.1%, respectively. It has been shown that the efficiency increases as the thickness of the nanofiber layer increases.