Solution-Processed Organic Hole Selective Layer Achieves 81.6% Fill Factor in Conventional Silicon Solar Cells

High-efficiency solar cells require effective carrier selective contacts which are depicted by their contact resistance and carrier selectivity. Over the past few years, diffusion-free carrier selective contacts have been broadly investigated including a variety of metal oxides, poly (3,4-ethylenedioxythiophene) doped with poly(-styrenesulfonic acid) (PEDOT:PSS), amino acids, alkaline metal salts, etc.. In this work, we investigate a solution-processed, organic small-molecule materials, 2,5,8,11-Tetra-tert-butylperylene (TBPe) to serve as the carrier selective materials. TBPe is fluorescent blue emitters respectively, which have been used as a hole transport layer in organic light emitting diodes. Moreover, the highest occupied molecular (HOMO) level of the material matches to the valance band of Si which may facilitate hole transport in conventional silicon solar cells. The small-molecule material is separately dissolved in chlorobenzene (CB), chloroform (CF) and toluene, followed by blade-coating on to the rear side of a 4 cm2, conventional n+/p silicon solar cell. Without the front anti-reflective coating (ARC) the devices with TBPe achieves a fill factor of 81.6%, and power conversion efficiency (PCE) of 12.6%, respectively. We will present the contact resistance, band alignment, and device efficiency to evaluate the potential of TBPe to serve as the hole selective contact.