The Preparation Of Dimethyl Sulfoxide (DMSO)-doped PEDOT: PSS Thin Films And The Application In The Organic Solar Cells

In recent years, organic solar cells have made great progress. Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a new type of conductive polymer, have caused widespread concern of researchers. Because it has the advantages:structure stability and high conductivity in the air. It is reported that adding high boiling point polar organic solvents can further improve the conductivity of PEDOT:PSS films, such as:dimethyl sulfoxide, sorbitol, glycerol, etc. The improved PEDOT:PSS as a conductive polymer material with high conductivity, has been widely used in various fields such as:electroluminescence, organic solar cells and other organic semiconductor devices, etc.Numerous studies show that adding high boiling point polar organic solvents can increase the conductivity of PEDOT:PSS,but there is a lack of systematic exposition in its physical nature and modification mechanism. The main works of this paper are listed as following:Firstly, high conductivity PEDOT:PSS films have been fabricated using controlling variables by adding dimethyl sulfoxide(DMSO). We make research of the effect of DMSO content on conductivity of PEDOT:PSS films and its modification mechanism. The experimental results show that the conductivity of PEDOT:PSS film mixed with 4% DMSO (volume ratio) is the highest, with the increase of conductivity from 8.84×10-2S/cm to 89.69S/cm. At the same time the absorption spectrum, the FTIR spectra and AFM images show that the addition of DMSO does not change PEDOT: PSS molecular structure.Secondly, we study that the effect of unmodified and modified PEDOT:PSS as anode buffer layer on the performance of organic solar cell device. The results show that: the device with PEDOT:PSS as anode buffer layer has the better performance, with the increase of short-circuit current density (Isc) from 1.04 mA/cm2 to 9.77 mA/cm2, the increase of open circuit voltage (Voc) from 0.03V to 0.59V, the increase of fill factor (FF) from 24.7% to 48.01% and the increase of photovoltaic energy conversion efficiency (PCE) from 0.0079% to 2.77%. When the wt% of DMSO is 4%, the performance of modified PEDOT:PSS as anode buffer layer achieved the best one:the short-circuit current density is 14.56 mA/cm2, the Open circuit voltage is 0.57V, the energy conversion efficiency is 3.34%. Finally, we try to fabricate organic solar cells using full-solution method with doped PEDOT:PSS as a transparent anode. It has the advantages of low cost and having simple preparation method. The structure of the organic solar cell device is ITO/Cs2CO3/P3HT:PCBM/PEDOT:PSS. It is studied that the effect of annealing on the performance of the organic solar cell devices at different temperatures. We find that when the annealing temperature is 120℃, the performance of the device shows a better one. The photoelectric conversion efficiency of the device is 0.65%. Although the energy conversion efficiency (PCE) of the device only reached 0.65%, we can improve the performance of devices by different aspects such as joining the anode buffer layer or changing the annealing temperature.