Organic/silicon nanowires hybrid solar cells using isobutyltriethoxysilane incorporated poly(3,4‐ethylenedioxythiophene):poly (styrenesulfonate) as hole transport layer

Hybrid heterojunction solar cells (HHSCs) using c‐Si nanowires (SiNWs) as the absorber and poly(3,4‐ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) as the hole selective transport layer (HTL) have been drawing more and more attention due to low cost process as well as high power conversion efficiencies (PCE). However, strong hygroscopicity of the PEDOT:PSS film causes serious degradation of the HHSCs. To improve the stability of the HHSCs, a kind of silane impregnating agent, isobutyltriethoxysilane (IBTEO), was selected as the additive to be added in the PEDOT:PSS solution. The hydrophobicity of the PEDOT:PSS film is much improved by formation of the hydrophobic silicone. The contact area between PEDOT:PSS and SiNWs is dramatically enlarged and more stable Si‐O‐Si bonds were formed at the PEDOT:PSS/SiNWs interface. As a result, the performance and stability of the HHSCs have been significantly improved. A PCE of 18.2% and a FF of 80.5% were obtained for a champion full solution processed PEDOT:PSS/SiNWs HHSC with 1 vol% IBTEO addition. The PCE remains 78% of the initial value after exposed 300 h in the air for the sample with IBTEO added in the PEDOT:PSS solution, while only 7% left for the control device without IBTEO addition. With the isobutyltriethoxysilane additive, the hydrophobicity of the PEDOT:PSS film is much improved by formation of the hydrophobic silicone.The stability of the PEDOT:PSS/SiNWs hybrid heterojunction solar cell (HHSC) is improved significantly. The PCE of 18.2% was obtained on a full solution‐processed PEDOT:PSS/SiNWs HHSC with 1 vol% isobutyltriethoxysilane addition. A high fill factor of 80.5% was also achieved on the PEDOT:PSS/SiNWs HHSC.