Research On High Performance Polymer Solar Cell Based On High Light Utilization Efficiency

Bulk heterojunction(BHJ)polymer solar cells(PSCs)have attracted great interest in recent years owing to the scope for a wide range of chemical modifications,solution-processability,low-cost and potential for mass production.Efforts have far focused on exploring strong light harvesting organic materials,innovative electrode buffer layers,and novel structures to gain efficient and stable PSCs.The power conversion efficiency(PCE)of single junction PSCs has reached up to 14%.Despite these improvements in device performance is satisfactory,a huge potential of efficiency enhancement might be achieved in these devices.Due to the large bandgap,narrow spectral response,low carrier mobility and short exciton diffusion length of most polymer materials,the best thickness of photoactive layer of non-fullerene polymer solar cells is usually about 100 nm.This thickness is much thinner than the theoretical thickness required to absorb all incident light.If the light utilization efficiency can be effectively increased within a limited thickness of the photovoltaic active layer,the efficiency of the polymer solar cell can be significantly improved.This paper focuses on how to maximize the light utilization efficiency of PSCs to improve device efficiency.In this paper,two methods are used to solve this problem:ternary PSCs with broaden spectral response and PSCs with plasmonic effect.The main contents are as follows:a.We introduce the third component,nonfullerene acceptor IEICO,into binary PSC-based PBDTBDD:PC71BM to fabricate ternary PSC with one donor and two acceptors.By carefully tuning the third component ratio and cathode engineering,the resulting ternary PSCs show a power conversion efficiency(PCE)of 10.51%,greatly improved in comparison with binary PSCs-based PBDTBDD:PC71BM(7.86%)and PBDTBDD:IEICO(5.19%).In addition to extended light absorption,the third component IEICO could accelerate charge-carrier transfer,and decrease charge recombination and increase electron collection and ameliorate the device morphology to increase the contact area of the active layer and cathode buffer layer.This work demonstrated that ternary PSC incorporated with IEICO is a promising structure for producing high performance PSCs.b.To take advantage of the plasmonic effects of sharp-edged metal nanoparticles and the excellent electron collection ability of ZnO in PSCs,we designed and synthesized multifunctional bipyramid-Au@ZnO core-shell nanoparticles(Au@ZnO).These materials were integrated into inverted non-fullerene PSCs with a limited photoactive layer thickness.We conducted electron mobility,dissociation probability,and time-resolved photoluminescence testing.Our results were supported theoretical predictions.Promising PCE values of 10.88%and 13.67%were achieved for the PBDTBDD:ITIC and PBDB-TF:IT-4F-based PSCs with an Au@ZnO cathode buffer layer(CBL).This performance was superior to that of reference devices without an Au@ZnO CBL,which showed PCEs of only 9.09%and 11.86%,respectively.Our findings suggest great potential for the design of multifunctional CBL with good electron extraction and plasmonic properties for high performance PSCs.