High-performance and-stability graphene quantum dots-mixed conducting polymer/porous Si hybrid solar cells with titanium oxide passivation layer

Recently, conducting polymer/Si hybrid solar cells (HSCs) based on simple fabrication processes have become highly attractive due to their low cost, but low conductivity of the polymer, high reflection index of Si, and large recombination loss on the Si back contact are major drawbacks that should be solved for the practical applications. Here, we first report HSCs composed of graphene quantum dots (GQDs)-mixed poly (3,4-ethylenedioxythiophene) (PEDOT:GQDs)/ porous Si (PSi)/n-Si/titanium oxide (TiO _x, back passivation layer). Maximum power conversion efficiency (PCE) of 10.49% is obtained from the HSCs at an active area of 5 mm², resulting from the enhanced conductivity of the PEDOT:GQDs, the reduced reflectivity of Si (the increased absorption) by the formation of PSi, and the prevented recombination loss at the Si backside due to the passivation. In addition, the HSCs of 16 mm² active area maintain ∼78% (absolutely from 8.03% to 6.28%) of the initial PCE even while kept under ambient conditions for 15 d.