Efficient and Stable Hole-Transport Material for Solar Cells: from PEDOT:PSS to Carbon Nanotubes:PSS

Hole transport materials (HTMs) are crucial for achieving high power conversion efficiency (PCE) of solar cells, which has facilitated the development of novel HTMs. In this work, an effective HTM with high conductivity, effective hole-transport, and high stability is fabricated by combining carbon nanotubes (CNT) and PSS. High-dispersive CNT in PSS solution forms a uniformly CNT network without doping, which shows a high conductivity due to carrier highways from the CNT ballistic transport mechanism. The conducting network is not affected by the humidity of the air and enhances the device stability. A synergistic effect of CNT and PSS gives the CNT:PSS composition film a high work function and a full-area passivation contact with Si. Finally, the highest PCE of 23.30% for organic:Si solar cells is achieved with a fill factor (FF) of 84.4%. These data demonstrate that the CNT:PSS film has excellent hole transport characteristics, which can also be applied to other photoelectric devices.