Hole transporting layer(HTL) free organometal halide perovskite solar cells have shown great promise in simplifying device architecture,fabrication process and enhancing stability.However,the simple elimination of the HTL from the standard sandwiched configuration suffers from relatively poor device performance;additionally,the mechanism of the HTL-free perovskite solar cell is still unclear.Herein,we applied a one-dimensional modeling program wxAMPS to investigate the planar HTL-free perovskite solar cells by adjusting the absorber thickness,doping and the absorber/back contact band alignment.The simulation results reveal the importance of the moderate absorber thickness as well as the p-doping perovskite rather than intrinsic as in sandwich structure to the overall device efficiency.In the meanwhile,reducing the mismatching of the absorber/back contact by using higher work function back contact material in replacement of commonly utilized Au electrode is more favorable to improve the device performance.Through optimizing,high performance HTL-free perovskite solar cell with efficiency approaching 17%could be achieved.This study is helpful in providing theoretical guidance for the design of HTL-free perovskite solar cells.
The interface between graphene and organic layers is a key factor responsible for the performance of graphene-based organic solar cells(OSCs). In this paper, we focus on coating PEDOT:PSS onto the surface of graphene. We demonstrate two approaches, applying UV/Ozone treatment on graphene and modifying PEDOT:PSS with Zonyl, to get a PEDOT:PSS well-coated graphene film. Our results prove that both methods can be effective to solve the interface issue between graphene and PEDOT: PSS. Thereby it shows a positive application of the composited graphene/PEDOT:PSS film on graphene-based OSCs.
Heterojunction and sandwich architectures are two new-type structures with great potential for solar cells.Specifically,the heterojunction structure possesses the advantages of efficient charge separation but suffers from band offset and large interface recombination;the sandwich configuration is favorable for transferring carriers but requires complex fabrication process.Here,we have designed two thin-film polycrystalline solar cells with novel structures：sandwich CIGS and heterojunction perovskite,referring to the advantages of the architectures of sandwich perovskite（standard）and heterojunction CIGS（standard）solar cells,respectively.A reliable simulation software wxAMPS is used to investigate their inherent characteristics with variation of the thickness and doping density of absorber layer.The results reveal that sandwich CIGS solar cell is able to exhibit an optimized efficiency of 20.7%,which is much higher than the standard heterojunction CIGS structure（18.48%）.The heterojunction perovskite solar cell can be more efficient employing thick and doped perovskite films（16.9%）than these typically utilizing thin and weak-doping/intrinsic perovskite films（9.6%）.This concept of structure modulation proves to be useful and can be applicable for other solar cells.
Tianyue WangJiewei ChenGaoxiang WuDandan SongMeicheng Li
