Nitrogen Compounds Hybrid Conducting Polymers For Photovolatics

Lignosulfonate(LS)is an excellent dispersant and dopant that comes from the byproduct of pulping process,which has been applied to prepare the LS doped poly(3,4-ethylenedioxythiophene)PEDOT(PEDOT:LS)conducting polymer aqueous dispersion.Moreover,PEDOT:LS has been applied in solar cells,light emitting diodes and supercapacitors.For further enhancing the performance of PEDOT:LS in organic solar cell(OSC)and organic-inorganic hybrid perovskite solar cell(PSC),I proposed to apply nitrogen compounds of octadecyl sulfonyl betaine(ODSB)and poly(diphenylamine-4-sulfonic acid)(PPSPA)to cooperate with LS to prepare novel PEDOT conducting polymers with superior electrical conductivity and highest occupied molecular orbital(HOMO)energy level.Firstly,a nitrogen compound of ODSB containing N⁺was applied to cooperated with LS to prepare PEDOT:LS:ODSB conducting polymer and PEDOT:LS was also prepared for comparison.It was found that PEDOT:LS:ODSB exhibited a higher electrical conductivity than that of PEDOT:LS.This phenomenon can be ascribed to the electron-withdraw ability of N⁺in ODSB that is beneficial for promoting the polymerization,doping and stacking of PEDOT in the emulsion polymerization process of PEDOT:LS.Moreover,we found that ODSB has no obvious effect on the other physicochemical properties of PEDOT:LS dispersion and film,such as dispersion dispersing stability,film-formation capability,activity and film optical transmittance,waterproofness property and HOMO energy level.Based on the superior electrical conductivity of PEDOT:LS:ODSB,the OSC with PEDOT:LS:ODSB hole transporting layer(HTL)exhibited a higher power conversion efficiency(PCE)of 5.56%than PEDOT:LS based OSC with a PCE of 4.92%.Meanwhile,PEDOT:LS:ODSB based OSC exhibited a comparable stability to that PEDOT:LS based OSC owing to the comparable waterproofness capability between the two HTLs.Secondly,a nitrogen compound of conductive polyaniline PPSPA was applied to cooperated with LS to prepare PEDOT:LS:PPSPA conducting polymer and PEDOT:LS was also prepared for comparison.It was found that PEDOT:LS:PPSPA exhibited higher electrical conductivity of 6.7x10^-4 S·cm^-1 and deeper HOMO energy level of-5.20 e V than those of PEDOT:LS(3.9x10^-4 S·cm^-1,-5.14 e V)which are even higher than those of standard HTL of poly(styrene sulfonic acid)doped PEDOT conducting polymer.The deeper HOMO energy level of PEDOT:LS:PPSPA can be ascribed to the strong oxidation behavior of its dopants of LS:PPSPA.Moreover,we found that PPSPA has no obvious effect on the other physicochemical properties of PEDOT:LS dispersion and film,such as film-formation capability and activity,and waterproofness property.Based on the superior electrical conductivity and HOMO energy level of PEDOT:LS:PPSPA,the PSC with PEDOT:LS:PPSPA HTL exhibited a higher PCE of 12.04%than PEDOT:LS based PSC with a PCE of 10.05%.Moreover,the PCE of PEDOT:LS:PPSPA PSC is even higher than that of PEDOT:PSS standard PSC(11.67%),suggesting the great potential of PEDOT:LS:PPSPA in HTL.