Degradation Behavior of PTB7:PC71BM and P3HT:PC71BM Organic Solar Cells with a TiOx Interlayer
In this study, the organic photovoltaic with bulk heterojunction (BHJ), thieno(3,4-b)-thiophene/ benzodithiophene copolymer and (6,6)-phenyl C71 butyric acid methyl ester (PTB7/PC71BM) treated with titanium oxide (TiOx) interlayer was fabricated and compared with the stability of organic solar cells based on poly (3- hexylthiophene) and [6,6]-phenylC71 butyric acid methyl ester (P3HT/PC71BM) with TiOx interlayer. TiOx was prepared by sol-gel chemistry method. The crystalline structure of TiOx was described by X-ray diffraction (XRD) while the absorption spectrum, and surface morphology of the BHJ were studied by UV-Vis spectroscopy and atomic force microscopy (AFM) respectively.
Organic solar cells were fabricated by spin-coating PEDOT:PSS layer on the top of ITO glass substrate. After annealing, the substrates were then transferred into a nitrogen filled glove box for spin-casting photoactive layers. Then TiOx layer was spin coated in air. Subsequently, aluminum (Al) electrode was deposited, producing the devices active area of ~ 10 mm2. Finally after Al deposition, the P3HT/PC71BM device was subjected to annealing treatment in glove box.
The electrical properties of the resultant devices were investigated by measuring the current density–voltage (J–V). Also the normalized efficiency of both devices as a function of time has been measured and stability was analyzed in terms of optical, structural and morphological degradation.
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