Novel approach to enhance efficiency of hybrid silicon-based solar cells via synergistic effects of polymer and carbon nanotube composite film

In this work, we put forward an effective approach by combining both highly transparent and conductive carbon nanotube (CNT) network and poly (3, 4-ethylene dioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) film to co-form-coordinate heterojunctions with silicon, and have developed a hybrid PEDOT: PSS-CNT/n-Si solar cell. The power conversion efficiency (PCE) of the as-designed solar cell can be improved up to 10.2%, which is much higher than the PCE values of both PEDOT: PSS/n-Si (5.5%) and CNT/n-Si (6.1%) solar cells fabricated using the same materials and process. PEDOT: PSS can fill the hundreds nanometer scale pores of the CNT network, both CNT network and PEDOT: PSS patches contact with the silicon concomitantly and form pSynergy-n heterojunctions through seamless contact with n-Si. The PEDOT: PSS-CNT composite film exhibits a much lower sheet resistance and remains high optical transmittance. Once the photo-generated holes are extracted to the PEDOT: PSS-CNT composite film, CNT network can serve as a carrier transport bridge, which is different from the design that inserts an ultrathin polymer between the CNT and Si. Incorporation of the continuous CNT network with PEDOT: PSS jointly in the as-designed simple and explicit structure has generated synergistic effects, which can make full use of the respective merits and then considerably enhance the PCE of hybrid PEDOT: PSS- CNT/n-Si solar cells.