Performance improvement of n-i-p μc-Si:H solar cells by gradient hydrogen dilution technique

High pressure radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process was adopted to investigate the effect of constant hydrogen dilution technique and gradient hydrogen dilution technique on the structural evolution of intrinsic films and the performance of n-i-p microcrystalline silicon solar cells. The experiment results demonstrated that the grain size and crystalline volume fraction along the growth direction of intrinsic films can be controlled and the performance of solar cells can be greatly improved by gradient hydrogen dilution technique. An initial active-area efficiency of 5.7% (Voc=0.47 V, Jsc=20.2 mA/cm2, FF=60%) for the μc-Si:H single-junction n-i-p solar cells and an initial active-area efficiency of 10.12% (Voc=1.2 V, Jsc=12.05 mA/cm2, FF=70%) for the a-Si:H/μc-Si:H tandem n-i-p solar cells has been achieved.