| In this paper, the emphasis is focused on the hole transport efficiency of small molecule organic solar cells based on CuPc/C60/LiF. The factors, such as the anode of the treatment conditions, choice of anode modification layer, which affect the hole output efficiency of small molecule organic solar cells were investigated. Moreover, optimization of device structure and analysis of the interface between the device layers, electrical properties and band structure of materials, the device's electrical characteristics, attenuation characteristics of the device were also studied.In this work, the in?uence of different indium tin oxide (ITO) surface treatments on the performance of organic solar cells was investigated. It was found that the surface treatments changed the parameters of the ITO (work function, carrier concentration, sheet resistance, surface roughness, et al) and significantly in?uenced the solar cell performance. After acid treatment, alkali treatment, and UV ozone treatment, ITO substrates were made to three cells and their performance was compared. The power conversion efficiency of the ITO/CuPc/C60/LiF /Al cell with optimal surface treatment is larger than that of the solar cell fabricated on untreated ITO substrate.The performances of small molecule organic solar cells based on CuPc/C60 were studied,including CuPc/C60 cells without any anode buffer layers and cells with Zinc-phthalocyanine (ZnPc), PEDOT:PSS, PEDOT:PSS/ZnPc system as an anode buffer layer, respectively. The mechanisms of these three kinds of anode buffer layers were discussed. The results show that ZnPc layer increases the open-circuit voltage from 0.372 to 0.479V. PEDOT:PSS layer increases the short- circuit current density from 1.943 to 3.752 mA/ cm2. The PEDOT:PSS/ZnPc system enhances both of them. The open-circuit voltage increases from 0.372 to 0.482 V. And the short- circuit current density increases from 1.943 to 3.810 mA/ cm2 and the power conversion efficiency increases more than 2 times. It is found that the main reasons of these superior improvements come from that ZnPc can make holes transport easily and PEDOT:PSS can smooth the surface of ITO.Although electrode buffer layer can improve the performances of the organic cells, sometimes it may decrease the stability, such as the PEDOT:PSS layer. PEDOT:PSS has a strong ability to absorb H2O vapor from the environment. And PSS is very easy to diffuse into other layers. So the performances of the cells with a single PEDOT:PSS layer attenuate rapidly. When the PEDOT:PSS/ ZnPc system is used, the ZnPc layer will slow down the diffusion velocity of H2O into the PEDOT:PSS layer and decelerate the PSS permeate into the other layers. Additionally, the double built-in field in the structure formed by the PEDOT:PSS/ ZnPc /CuPc system can effectively prevent the H+ in the wet PEDOT:PSS layer from permeating into the active layers. Because of these factors, the stability of the cells with a PEDOT:PSS/ZnPc anode buffer layer system can exhibit the best stability.In summary, the PEDOT:PSS /ZnPc anode buffer layer system utilizes both advantages of a single LiF anode buffer layer and a single PEDOT:PSS buffer layer. Moreover the performances of the cells are further improved. Meanwhile, this anode buffer layer system overcomes the shortages on stability of the cells with a single buffer layer.In addition, the optical propagation matrixes were calculated. The intensity distribution inside CuPc/C60/LiF cells was analyzed. The results of the intensity distribution inside the cell of ITO(220nm) /LiF(1nm) /CuPc(20nm)/C60(40nm)/Al(100nm) and ITO(220nm) /PEDOT:PSS (20nm) /CuPc(20nm)/C60(40nm)/Al(100nm) ITO(220nm)/CuPc(20nm)/C60(40nm)/Al(100nm) were given out, in which the light wavelength used was 632.8nm. Compared with the intensity distribution inside CuPc/C60/LiF cells, there only a very small difference exists between curves. Therefore, whether ZnPc layer or PEDOT: PSS layer does not affect the performance of the battery from the view of absorbing light energy.
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