Synthesis And Properties Of Novel Sensitizers And Hole Transport Materials Containing Triphenylamine Units

N,N,N’,N’-tetraphenyl-benzidine（TPB） and their derivatives, as one essential HTM, has been widely used in diverse organic electronic devices such as organic light emitting diode（OLED）, organic field-effect transistor（OFET）, oganic photoconductor（OPC）. In this paper,we have chosen TPB as the skeleton and designed a series of organic dyes and small molecule HTMs. And we applied these materials in DSCs and PSCs successfully. The highest PCE is 5.15% and 13.10%, respectively.Six TPA-based organic dyes, which contain the typical electron donor-π conjugation-electron acceptor（D-π-A） structure, were designed and synthesized. The structures of the dyes and intermediates were characterized by MS, 1H NMR, 13 C NMR and HRMS. The quantum chemistry calculation of these photosensitizers was performed based on density functional theory（DFT）. And the calculation result illustrated that the highest occupied molecular orbital（HOMO） of all photosensitizers mainly distributed in TPB moiety. Their lowest unoccupied molecular orbital（LUMO） were in the carboxyl groups. Photophysical properties of the as-synthesized dyes were investigated and the infulence of the structure on the photophysical properties has been discussed. The ICT absorption peaks shifted about 1nm¹5nm when photosensitizers absorbed on TiO₂ film. Electrochemical properties of the photosensitizers were examined by cyclic voltammetry measurement. The estimated LUMO energy level was from-2.28eV^-3.32 eV and the HOMO energy level was from-5.33eV^-5.65 eV, which suggested that all photosensitizers can satisfy the need of charge injection and the regeneration of oxidized dyes. The adsorbance of as-synthesized dyes has been obtained and the relationship between molecular structure and adborbance has been discussed. The incident photon-to current conversion efficiency（IPCE） and currentvoltage（J-V） curves of the DSCs based on the as-synthesized dyes were measured. The ralationship between dye structures and photovoltaic performance of the DSCs were studied. The DSCs based on D4 showd wider IPCE range and higher open-circuit voltage（Voc）, thus the best performance with the conversion efficiency of 5.15% was obtained.In this paper, we report the synthesis and characterization of two TPB-based HTMs（TPBS and TPBC）, as well as their application in perovskite solar cells. The cyclic voltammetry measurement has shown that by modifying the structure of TPB, not only the energy levels of the HTMs are tuned, but also the galss transition temperatues and hole transporting mobilities are increased. The device, fabricated with TPBC as HTM, affords an open-circuit voltage（Voc） of 942 mV, a short-circuit current density（Jsc） of 19.32 mA/cm2 and a fill factor（FF） of 0.72, leading to a PCE of 13.10% under AM 1.5G（100mW·cm-2） illumination. The electrochemical impedance spectroscopy analysis result indicates that TPBC as the HTM can prevent charge recombination, leading to a higher Voc. The time-resolved photoluminescence decay measurement result indicates fast charge transfer from perovskite at the CH3NH3PbI3/TPBC interface. In summary, TPBS and TPBC are successfully synthesized by a simple process with low cost and their performance is comparable to that of spiro-OMeTAD. This results provide compelling evidence for the first time that small-molecule HTMs with TPB core have great potential for the application in high efficient doping-free perovskite solar cell.