Ultrathin Al₂O₃ interface achieving an 11.46% efficiency in planar n-Si/PEDOT:PSS hybrid solar cells

Hybrid organic-inorganic photovoltaic devices consisting of poly(3,4-etyhlenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type silicon have recently been investigated for their cost-efficiency and ease of fabrication. We demonstrate that the insertion of an ultrathin Al₂O₃ layer between n-Si and PEDOT:PSS significantly improves photovoltaic performance in comparison to the conventional interfacial oxide employing SiO₂. A power-conversion efficiency of 11.46% was recorded at the optimal Al₂O₃ thickness of 2.3 nm. This result was achieved based upon increased built-in potential and improved charge collection via the electron blocking effect of Al₂O₃. In addition, the hydrophilicity enhanced by Al₂O₃ improved the coating uniformity of the PEDOT:PSS layer, resulting in a further reduction in surface recombination.