Synthesis And Photovoltaic Properties Of N,N-diphenylhydrazone Dyes And Conjugated Polymers Based On Diindenopyrazine

In this dissertation, the research progress of the materials and devices ofdye-sensitized solar cells (DSSCs) and polymer solar cells (PSCs) were summarizedsystematically. In order to study on the influence of π-conjugated bridges onphotoelectric properties in dyes and control of molecular orbital energy levels,absorptions, bang gaps and charge mobilities of the conjugated copolymers, a seriesof novel D-π-A hydrazone dyes and conjugated copolymers based on the6,12-dihydro-diindeno[1,2-b;1’,2’-e]pyrazine had been designed and synthesized. Thestructures of the as-synthesized compounds were proved and confirmed by1H NMR,13C NMR, FT-IR and element analyst. The photophysical and electrochemicalproperties of the dyes and copolymers have been investigated by UV-vis spectra,photoluminescence spectra and cyclic voltammetry. At the same time, thephotovoltaic performances of solar cells based on the as-synthesized dyes andcopolymers were measured. The main results are as follows:1, A series of novel D-π-A hydrazone dyes (HB, HP, HF and HT) containing a N,N-diphenylhydrazone donor and2-cyanoacetic acid acceptor bridged by a differentaromatic bridge (benzene, pyrrole, furan, and thiophene) have been designed andsynthesized for dye-sensitized solar cells (DSSCs). We systematically studied theeffects of electron donor and different π-bridges on the photophysical,electrochemical properties, and photovoltaic performances. The results suggest that N,N-diphenylhydrazone and N-(2-ethylhexyl)pyrrole can be used as an alternative andeffective donor and π-conjugated bridge, respectively, in efficient D-π-A organic dyes.A DSSC based on the dye HP showed the best photovoltaic performance: ashort-circuit photocurrent density (Jsc) of14.76mA/cm~2, an open-circuit photovoltage(Voc) of0.69V, and a fill factor (FF) of0.705, corresponding to an overall powerconversion efficiency (PCE) of7.18%under standard global AM1.5solar conditions.2, Three novel D-π-A hydrazone dyes (HM, HE, HO) with an N,N-diphenylhydrazone moiety as the electron donor, different thiophene-derivedπ-conjugated bridges and a cyanoacrylic acid moiety as the electron acceptor havebeen designed and synthesized for the application in DSSCs. The influences ofthiophene-derived bridges on the photoelectrochemical and photovoltaic performanceof these hydrazone dyes were investigated. The results of calculation and experimentsclearly demonstrate that photoelectrochemical properties can be regulated by introducing different thiophene-derived π-conjugated bridges. Among the three dyes,HO exhibits the maximum PCE of5.83%(Voc=0.65V, Jsc=12.69mA/cm~2, FF=0.707) under simulated AM1.5irradiation (100mW/cm~2).3, A series of new copolymers (PIPY-DTBT, PIPY-DTBTA, PIPY-DTTT,PIPY-BT, PIPY-BDT, PIPY-TT) based on indeno[1,2-b;1’,2’-e]pyrazine (IPY)derivatives have been designed and synthesized for polymer solar cells (PSCs). Thethermal stabilities, photophysical, electrochemical, and photovoltaic properties of thesix copolymers were investigated in detail. The results show that IPY derivatives wereconsiderd as weak donors which are good for high Voc. At the same time, the bad gapsand molecular energy levels of copolymers can be easily tuned by copolymerizationwith different electron-rich and electron-deficient units. Photovoltaic cells werefabricated based on the blend of the as-synthesized copolymers and PC61BM in a1:2weight ratio, the PCEs of the six polymers are in the range of0.05%to0.77%.