High efficiency and stable hydrogenated amorphous silicon radial junction solar cells built on VLS-grown silicon nanowires

Hydrogenated amorphous silicon (a-Si:H) radial junction solar cells, built over a dense matrix of Si nanowires (SiNWs), benefit from strong light trapping. This allows the use of a very thin absorber layer without sacrificing the solar cell performance, while improving its stability. By optimizing the density of SiNWs grown via a plasma-assisted vapor–liquid–solid process on glass, we have achieved radial junction a-Si:H solar cells with an open circuit voltage of 0.80 V, short circuit current density of 16.1 mA/cm2 and a high power conversion efficiency of 8.14%. Furthermore, we present experimental evidence of the excellent stability of such radial junction a-Si:H solar cells with a light-induced degradation of only ~6%, compared to the typical degradation of 15% to 20% in planar cells. These results indicate the feasible and promising approach towards a new generation of stable and high performance a-Si:H thin film solar cells.