GaAs nanowire/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) hybrid solar cells with incorporating electron blocking poly(3-hexylthiophene) layer

In this report, we demonstrate a new type of hybrid solar cell based on a heterojunction between the vertically aligned GaAs nanowires and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with incorporating poly(3-hexylthiophene) (P3HT) electron blocking layer. Under 1 sun simulated AM1.5 G solar illumination, the fabricated cell exhibits the power conversion efficiency of 9.2%. The fabrication of GaAs nanowire array adopts the top-down approach, which combines the low-cost monolayer nanosphere mask fabrication and the dry etching process with high quality single-crystalline GaAs wafer. The P3HT/GaAs heterojunction with a large conduction band offset will block the electron transportation from GaAs to PEDOT:PSS. Therefore, the electron transports toward the favorable Ti/Au electrode. Moreover, it is observed that the thickness of P3HT significantly influences the cell performance. Only the ultra-thin thickness is suitable for P3HT to act as an electron blocking layer without the negative influences on the cell performance.