Heteroatom-doped graphene-like carbon films prepared by chemical vapour deposition for bifacial dye-sensitized solar cells

• The synthesis of N-doped, S-doped and N/S dual-doped GFs.
• The first report on DSSCs fabricated with CVD-derived doped GFs as CEs.
• Heteroatom doping can efficiently enhance the electrocatalytic activity of GFs.
• CVD-derived doped GFs are found to be one of the most promising materials for CEs in bifacial DSSCs.

Bifacial dye-sensitized solar cells (DSSCs) with the ability to utilize incidental light from both front- and rear-sides have drawn massive attention from researchers in recent years. Herein, nitrogen (N)-doped, sulphur (S)-doped and nitrogen/sulphur dual-doped transparent graphene-like carbon films (GFs) were synthesized by chemical vapour deposition (CVD) and confirmed by transmission electron microscopy (TEM), UV–Vis transmitted spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The doped GFs show good performance as counter electrodes (CEs) for fabrication of bifacial DSSCs. The bifacial DSSCs with high transparent N-doped, S-doped and N/S dual-doped GFs as CEs exhibit dramatically enhanced power conversion efficiency (PCE) of 3.74%, 3.86% and 4.22% under front-side illumination compared to that of pristine graphene as CEs. More importantly, under rear-side illumination the PCE of bifacial DSSCs with N-doped, S-doped and N/S dual-doped GFs as CEs can also reach 3.07%, 3.19% and 3.45%, suggesting that the doped GFs have great potential applications in fabricating bifacial DSSCs with high performance.