Synthesis And Photovoltaic Properties Of Photovoltaic Materials Based On Fullerene And Benzodithiophene

In this dissertation, we summarized the research status of organic solar cells(OSCs). In order to improve the power conversion efficiency (PCE) and stability ofOSCs, we designed and synthesized a pyridine-functionalized fullerene derivative, aclass of OSCs doner materials which contained benzodithiophen unit. The structure oftarget materials were unambiguously determined by X-ray diffraction or1HNMR,13CNMR and MS. Their thermostability, electrochemical properties and optical propertiesof these materials were also investigated by thermogravimetric analyses (TGAs),cyclic voltammetry (CV) and UV-vis absorption spectra. Additionally, thephotovoltaic properties of these materials well studied by farbricating the bulkheterojuncion devices. The key studies results of this paper are listed below:1) One pyridine-functionalized pyrazolinofullerene (M1) was designed andsynthesized. The structure of M1was further confirmed by single crystal X-raydiffraction. Compound M1was used as a buffer layer to modify ZnO in invertedpolymer solar cells, and the PCE was improved from3.65%to4.18%for the invertedP3HT: PC61BM based solar cells. This buffer layer is beneficial for the excitondissociation at the interface and could reduce contact resistance of the device, leadingto a higher Jscand FF.2) Two organic small molecules with benzodithiophene as donor unit, threethiophene as conjugated π bridge and cyanorhodanine as acceptor unit for end groupswere designed and synthesized. Both organic small molecules possess goodthermostability and broad absorption, and show good solubility in common organicsolvents, such as chloroform, chlorobenzene, etc. The PCE values of the OSCs basedon D(T3-DCRD)-BDT and D(T3-DCRD)-TBDT/PC61BM are1.10%and1.94%,respectively. The results indicate that the molecules with thienyl conjugated sidechains show better photovoltaic performance.3) A monomer with triphenylamine substituted benzodithiophene D(TPAT)BDTwas designed, and two polymers (PD(TPAT)BDT-BT and PD(TPAT)BDT-DPP) wereobtained utilizing this monomer copolymerization with benzothiadiazole anddiketopyrrolopyrrole. Both polymers possess good thermostability and broadabsorption, and good solubility in common organic solvents, such as chloroform,chlorobenzene. Compared with PD(TPAT)BDT-DPP, PD(TPAT)BDT-BT with highermolecular weight, and relatively small steric hindrance leading to easier exciton dissociation with PC61BM. So based PD(TPAT)BDT-BT have higher powerconversion efficiency (PCE): PCE=1.78%(Voc=0.69V，Jsc=5.34mA/cm2，FF=48%).