Light management of a‐Si:H solar cells using textured zinc oxide with adjustable haze values

Abstract

AbstractBoron doped zinc oxide (ZnO) films to be applied as transparent conductive oxide (TCO) in single junction pin hydrogenated amorphous silicon (a‐Si:H) solar cells were fabricated using metal organic chemical vapour deposition (MOCVD) technique. ZnO films with various haze values and surface root mean square (RMS) roughnesses were obtained by adjusting the thickness of films. B‐doped concentration presented a little effect on the RMS roughness of ZnO films but produced an adjustable sheet resistance. A series of ZnO films with a similar sheet resistance of ∼10 Ω/□ but different RMS roughnesses were applied in a‐Si:H solar cells as TCOs. The intrinsic a‐Si:H thin films with different thicknesses were used as the active layer of solar cells. It was found that the optimum RMS roughness strongly depended on the thickness of active layer. It was also confirmed that higher short‐circuit current density (Jsc) could be achieved by employing TCO with higher RMS roughness due to effective light trapping. A stabilized conversion efficiency of 9.3% and a Jsc of 16.9 mA/cm2 were obtained by utilizing ZnO TCO with a surface RMS roughness of 95 nm for a single junction pin a‐Si:H solar cell without any antireflective coating. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)