Preparation And Performance Study Of Flexible Single-component Organic Solar Cells

Against the backdrop of global warming and energy crises,there is a growing urgency for various types of renewable energy sources.Among them,organic solar cells（OSCs）with advantages of light weight,flexibility,and printability,have become a research hotspot and frontier field in recent decades.With the upgrading of organic semiconductor materials and the development of device fabrication technology,the power conversion efficiency（PCE）of bulk heterojunction（BHJ）OSCs has made breakthrough progress.BHJ OSCs are typically composed of a physically blended donor/acceptor light-absorbing layer material,which is prone to self-aggregation under conditions such as light exposure and heating,leading to the instability of the microstructure and rapid decline of PCE.In addition,the phase separation of the donor/acceptor material in the thin film results in a decrease in the mechanical properties of the light-absorbing layer,which is not conducive to the application of flexible organic solar cells（F-OSCs）.Single-component organic solar cells（SCOSCs）have a light-absorbing layer composed of a single material,which can effectively avoid the instability of efficiency and mechanical properties caused by the physical blending of donor/acceptor materials.However,research on the stability and mechanical properties of SCOSCs has been extremely limited in the past few decades.Therefore,this paper addresses the issues of mechanical flexibility and stability of F-OSCs.Through the preparation of a novel flexible electrode of silver nanowires,intrinsic mechanical properties research on double-cable single-component materials,and the construction of large-area flexible SCOSCs with polymer additive doping strategies,the advantages of single-component materials applied in F-OSCs have been demonstrated.Furthermore,the stability and PCE of SCOSCs have been improved by using a novel mesoporous SCOSCs device and the application of homojunction single-component materials.This provides a new solution for realizing the commercialization of high-stability and high-flexibility F-OSCs.The primary contents of this study are as follows:1.A simple and effective reduction bath immersion method has been developed to synchronously improve various properties of Ag NWs flexible transparent electrodes.The results indicate that a new Ag NWs@Sn O_xelectrode was prepared by reducing the Ag NWs film in the bath.The electrode exhibited enhanced electrical conductivity,lower roughness,and superior optical and thermal stability.Additionally,the Ag NWs@Sn O_xelectrode was more compatible with the light-absorbing layer material.Under 1 standard sun（AM1.5G）illumination,the flexible device achieved a high PCE of up to 16.6%.Under indoor illumination（1000 lux）,a flexible indoor organic solar cell with a PCE as high as 25.51%was successfully realized.2.The intrinsic mechanical properties of double-cable conjugated polymer JP02 were thoroughly investigated through the"Film-on-water"stretching method.The results demonstrate that JP02 possesses excellent elastic deformation and exceptional tensile strength.Based on JP02,flexible single-component organic solar cells（SCOSCs）were developed,achieving a PCE of 7.21%,as well as outstanding bending stability and storage stability.Moreover,a highly flexible single-component organic solar cell with a total thickness of less than 2μm was prepared using the JP02 polymer.3.By utilizing the strategy of non-conjugated insulating polymer doping,the mechanical properties of SCOSCs have been greatly improved,and it has been demonstrated that miscibility is the key factor in determining both photovoltaic performance and mechanical properties.The study found that as the miscibility between the doped insulating polymer and the double-cable conjugated polymer JP02 increases,the crystallinity of JP02 remains unchanged,while the crystallite size becomes smaller.Thus,while ensuring charge transfer,the mechanical properties of JP02 are significantly improved.Specifically,JP02 exhibited an increase in elongation at break from 3.1%to 4.69%upon doping with 15%PS.Furthermore,we demonstrated the effectiveness of doping strategy in enhancing the mechanical stability of flexible SCOSCs.4.Through the construction of flexible and large-area SCOSCs devices,the advantages of single-component materials in improving device reproducibility have been demonstrated.The research indicates that the dual-cable conjugated polymer as-DCPIC,as a single-component material,exhibits homogeneous solution viscosity and film-forming properties,with uniform lateral distribution.This effectively alleviates the problems of large efficiency gaps and low device repeatability in large-area F-OSCs devices.Additionally,as-DCPIC has a fracture elongation rate of more than 9%,and large-area flexible SCOSCs based on as-DCPIC exhibit a PCE of up to 9.45%and excellent mechanical stability.5.By introducing a mesoporous Ti O₂ scaffold layer,the long-term stability of photovoltaic devices has been improved.Compared with the traditional planar device structure without mesoporous Ti O₂ layer,the mesoporous Ti O₂ layer can ensure the high efficiency of charge carrier extraction and stable morphology of the absorbing layer in the continuous light illumination process.After continuous light illumination for 300hours,the photovoltaic conversion efficiency can still maintain more than90%of the initial value.The results demonstrate that the introduction of mesoporous Ti O₂ layer can significantly enhance the morphological stability of the absorbing layer and the stability of photovoltaic devices.6.We designed and synthesized three different small molecule acceptors,namely Y series,with varying alkyl chain lengths.Through photovoltaic device characterization,we investigated the effect of alkyl chain length on charge transfer and device performance.Furthermore,by introducing a Cu SCN hole-extraction layer,we significantly enhanced the power conversion efficiency（PCE）of homojunction SCOSCs.Our research revealed that Y6-C2,with a shorter alkyl side chain,exhibited a denser crystalline morphology and higher hole mobility.A PCE exceeding4.5%was achieved using homojunction SCOSCs based on Y6-C2 small molecule acceptor.