The Synthesis And Characterization Of All-organic Photoelectric-conversion Functional Semiconductor With A Thiophene Unit

Although,the cells employ ruthenium polypyridyl complexes as charge-transfer sensitizers,yielding over 11%solar-to-electric power conversion efficiencies under AM1.5 G sunlight,the ruthenium polypyridyl complex can not be used widely due to its high-cost and pollution.Organic dyes are promising for application in DSC in that they have much higher molar extinction coefficients and lower cost than those for ruthenium polypyridyl complexes,which are becoming more and more polular and chart a new direction.According to the demand of dye-sensitized solar cells and the tendency of development,we designed two organic dyes coded C201 and C203 which have the D-Ï€-A structure.These sensitizers were synthesized in three steps:Suzuki Coupling,Vilsmeier-Haak reaction and Knoevenagel Condensation.The performance and structure of the two dyes were investigated by UV-Vis, square-wave voltammetry and NMR,and the data show that C201 and C203 have high molar extinction coefficients and suitable redox potentials.These dyes have achieved 8.0%,7.8%power-conversion efficiency(η) respectively,with 1.0 M DMâ…¡,30 mMâ… ₂,0.1 M GNCS,0.5 M TBPY in AN/VN(85/15,v/v) as electrolyte under AM1.5 G full sunlight,and 7.0%with DMâ…¡/ EMâ…¡/ EMITCB /â… ₂/NBB / GNCS(12 / 12 / 16 / 1.67 / 3.33 / 0.67) as electrolyte.After a 1000 h aging test, the data of devices performance only changed a little,it is impressive that the high efficiency DSC with all-organic sensitizers have showed an excellent stability measured under the dual stress of thermal stress and light-soaking.Furthermore, for the first time we have achieved 4.7%efficiency for all-solid-state dye-sensitized solar cells based on a metal-free organic dye C201.C203 has a low free energy of salvation due to its fused dithionothiophene,eliminating the dye-desorption during the long-term device operation. We designed and synthesized two organic dyes coded C202 and C206 in order to study how the donor impact the electronic absorption spectra.Through comparing the UV-absorption spectra of C201,C202 and C206,we got a conclution that the electron donating group would make the absorption red-shift, meanwhile,the long branches can improve the dissolvability of dye,having little impact to the absorption.