Research On High Performance Semitransparent Polymer Solar Cell

Bulk heterojunction polymer solar cells have attracted widespread attention due to their low cost,light weight,large area processing,and semitransparent.With the continuous research,more and more materials and structures have been developed.At present,the efficiency of polymer solar cells has exceeded 17%.Semitransparent polymer solar cells show great potential in building integrated photovoltaics due to their low cost in large-area manufacturing processes and their bright colors that can be used for power generation glass.However,the contradiction of achieving a high average photoelectric conversion efficiency while maintaining a reasonable average visible transmittance has led to the development of semitransparent polymer solar cells lagging behind the traditional opaque polymer solar cells.The purpose of this thesis is to resolve this contradiction,introduce interface modification layers with high transmittance and good performance,and further improve the visible transmittance while ensuring the high efficiency of the device.The main contents are as follows:a.MoO3 is a promising anode interfacial layer with high work function for polymer solar cells.However,due to the limited electron blocking ability,the interfacial recombination occurs seriously in the MoO3/organic interface.To reduce the interfacial recombination,we introduced minimal amount of NiOx into MoO3 to enhance the electron blocking ability of anode interfacial layer.The MoO3 mixed with NiOx layer(MoO3:NiOx)is highly transparent with a conduction band of 3.25 eV and a work function of 5.10 eV,which prolongs the electron lifetime of PBDB-T:IT-M based device from 0.63 to 5.05μs.Benefiting from the prolonged lifetime and enhanced charge collection of MoO3:NiOx anode interfacial layer,the power conversion efficiency of PBDB-T:IT-M based semitransparent devices is significantly improved to 8.77%,much higher than that of devices with PEDOT:PSS(8.04%),M0O3(7.34%)and NiOx(7.72%)anode interface layers,and the average visible transmittance has also improved compared to traditional devices using PEDOT:PSS,from 14.22%to 15.93%.b.We designed and synthesized a multifunctional SnO2 interface layer and systematically investigated the synergistic effects of interfacial and optical engineering,finally high performance semitransparent polymer solar cells with multicolor are demonstrated.Under the guidance of finite-different time-domain(FDTD)and optical transfer matrix formalism(TMF)simulation,ultrathin Ag film with optimized transparency was employed as the transparent electrode,SnO2 film with high up to 95%transparency and outstanding hole blocking ability was used as cathode buffer layer,and the multiple donor-acceptor combinations with optimized thickness and exciton distribution was adopted as photoactive layer in the inverted semitransparent polymer solar cells.Taking the joint benefits of each functional layer,semitransparent devices with five different colors including green,sky-blue,deep-blue,violet and fuchsia are realized and exhibit good performance,meeting the requirements of beauty.Among them,the deep blue device shows the highest power conversion efficiency of 12.88%,average visible transmittance of 25.60%(from 370 nm to 740 nm)and color rendering index of 97.6,fulfilling the performance criteria for commercial application as power-generating windows in near future.