Enhanced performance of Si/PEDOT: PSS heterojunction solar cells via multi-walled carbons coated with polydopamine

n-Si/PEDOT: PSS heterojunction solar cells are expected to be the alternative for photovoltaic technique for the potentially excellent power conversion efficiency and ease of processing. Herein, a multi-walled carbon nanotubes network coated with polydopamine (MWCNTs&PDA) was applied as an interlayer between silicon substrate and PEDOT:PSS film to enhance the performance of Si/PEDOT:PSS heterojunction device in this study. When the film was applied as an interlayer, the average reflectance of the device within the wavelength range 400–1000 nm dropped from 13.6 % to 8.33 %. The enhanced antireflection ability meant more photon-generated carriers were excited. The introduction of PDA reduced the contact angle from 84.5° to 47° on Si surface, and the minority carrier lifetime (τ) was 2.16 times increase. The high charge separation and improved junction effect of MWCNTs&PDA films incorporated between PEDOT:PSS and Si substrate result in advantageous networks of charge carriers, which is confirmed by the excellent open-circuit voltage (V oc ) 637 mV, short-circuit current density (J sc ) J sc 34.76 mA/cm 2 and fill factor (FF) 56.41 %. The power conversion efficiency improved to 12.49 % when the MWCNTs&PDA film was incorporated. The achievements of this study indicated that the MWCNTs coated with polydopamine as an interlayer is a promising material for excellent performance Si/PEDOT:PSS heterojunction solar devices.