Synthesis Of Phenoxazine Derivatives And Their Photoelectrochemical Properties For Dye Sensitized Solar Cell

Dye-sensitized solar cells (DSSCs) have attracted considerable and sustained attention in recent years due to their ease of fabrication, high efficiency, and cost-effectiveness. Organic sensitizers containing phenoxazine have recently attracted considerable research interests on account of their unique excellent optical property. A series of new phenoxazine small dyes was developed to achieve pure organic dyes with high efficiency and stability. Then synthesis, characterization, photophysical and electrochemical character was studied and analyzed to obtain the relationship and corresponding rules between structure and properties.(1) Three dyes based on POZ unit have been synthesized. Electron-rich3,4-ethylenedioxythiophene (EDOT) unit has been used as n linker to broaden the optical absorption and optimize torsion angle., RPOZ-1was obtained with the introduction of EDOT between the unit of POZ and thiophene based on RPOZ. TPA substituted with isooctyl groups was attached to the7position of POZ unit to form RTPAPOZ. RTPAPOZ-1was achieved through inserting EDOT between the structure of TPA and POZ.(2) It was found that with the introducing of alkoxy-substituted triphenlamine electron-donor (D) and electron rich EDOT π linker to the RPOZ unit, the absorption peaks of these dyes are red-shifted compared to RPOZ by UV-Vis absorption spectra, and the RPOZ-1dye shows the broadest absorption and highest molar absorption coefficiency. According to the optimized geometries, the introduction of EDOT can decrease dihedral angle of molecule structure to optimize conjugate performance. RPOZ-1shows the best conjugate performance, while the conjugate property of RTPAPOZ-1is superior to RTPAPOZ. The conjugate performance of three dyes was ranked:RPOZ-1>RTPAPOZ-1>RTPAPOZ.(3) The photoelectrochemical properties of four new dyes have been studied in DSSC. The responding range of IPCE curve is in good agreement with the UV-visible absorption spectra. The device sensitized by dye RTPAPOZ obtained the best conversion efficiency of2.73%(Voc=680mV, Jsc=10.18mAcm-2). The RPOZ-1sensitized solar cell exhibits the higher Jsc among these cells based on phenoxazine dyes, while the Voc shows the lowest. Therefore, it was discussed and analyzed about the influence factors of photoelectric properties in the article as well as the ways to improve the conversion efficiencies.