Design And Synthesis Of New Double-cable Polymers And Their Application In Single-component Organic Solar Cells

The double-cable conjugated polymer is comprised of conjugated donor backbone and acceptor side unit connected by an alkyl chain,making it applicable as one component in single-component organic solar cells.Single-component organic solar cells can avoid the self-aggregation issue of donors and acceptors encountered in two-component organic solar cells,thereby enhancing device stability.However,due to the relative scarcity of material and the ambiguity of morphology structure,the power conversion efficiency of single-component organic solar cells still lags far behind that of two-component systems.In light of this,we focus on double-cable conjugated polymers and strive to enhance the performance of single-component organic solar cells.Through a series of innovative synthesis methods,various new double-cable conjugated polymers have been successfully synthesized.By the morphology manipulation of the double-cable polymers and applying them to single-component organic solar cells,we aim to explore the relationship between molecular structure,morphology and photovoltaic performance.The specific research contents are as follows:1.Designed and synthesized a series of double-cable conjugated polymers based on rigid connecting chains(P1-P3).These materials utilize one,two or three phenyl units to link the donor backbone and acceptor side unit.Theoretical calculations and experiments showed that as the donor-acceptor distance increased(from P1 to P3),the non-radiative recombination loss of the devices decreased,leading to an increase in open-circuit voltage.Moreover,transient absorption tests showed that single-component organic solar cells based on P3 exhibited stronger charge extraction capabilities.Therefore,P3-based single-component organic solar cells achieved an open-circuit voltage of 0.84 V,a short-circuit current density of 8.64 m A/cm2,a fill factor of 0.546,and a power conversion efficiency of3.97%.This study established a causal relationship between the donor-acceptor distance and non-radiative recombination loss,providing important reference for designing single-component organic solar cells with high open-circuit voltage.2.Efficient synthesis of double-cable conjugated polymer DCPIC1containing non-fused"A-π-D-π-A"type acceptor side groups was achieved through a synthetic route of"functionalization first,end-capping later,and polymerization last".DCPIC1 exhibited absorption extending to the near-infrared region,with absorption in the range of 300-800 nm.Single-component organic solar cells based on DCPIC1 achieved a short-circuit current density of 10.55 m A/cm~2.However,due to the excessively large size of DCPIC1’s film phase separation,its single-component solar cells only achieved a photovoltaic conversion efficiency of 3.76%.Nevertheless,the design and synthesis of DCPIC1 also provided insights for designing double-cable conjugated polymers based on A-π-D-π-A type acceptors,thus promoting the development of novel double-cable conjugated polymers.3.The strategy of asymmetric substitution was employed to introduce the fused electron acceptor Y6 into double-cable conjugated polymers,leading to the design and synthesis of DCP-Y6.DCP-Y6 exhibited a broad absorption range of 300-900 nm,significantly enhancing the material’s utilization of sunlight.Meanwhile,DCP-Y6 showed superior film morphology and charge carrier mobility,and its single-component solar cell achieves a power conversion efficiency of nearly 10%.The design,synthesis,and application of DCP-Y6 promoted the development of Y-series acceptors in single-component solar cells,providing guidance for further designing high-performance double-cable conjugated polymers.4.By utilizing connection points on the central core and employing a strategy of random copolymerization,double-cable conjugated polymers containing Y-series acceptors were synthesized.The acceptor side group Y-O6not only provided connection points but also exhibited high crystallinity.This high crystallinity ensured the ordered stacking of acceptors in the double-cable polymers,thereby forming excellent electron transport channels.Furthermore,the strategy of random copolymerization optimized the bipolar charge transfer and nano-phase separation in DCPY2,ultimately achieving a record-breaking photovoltaic conversion efficiency of 13.02%in single-component organic solar cells.The study indicated that high charge carrier mobility and more ordered stacking structure are key to achieving high-performance single-component organic solar cells,while the introduction of Y-series acceptors provides new tools for further improving the performance of single-component organic solar cells.