Binary and ternary molecules blend bulk heterojunction organic solar cell.
Mkhwanazi, Emmanuel Khulekani.
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Bulk heterojunction organic solar cells were prepared and characterized in terms of electrical and optical properties of the photosensitive medium. Two cases of organic solar cells were developed in this investigation with active layers composed of P3HT:PCBM molecules blend and P3HT:PTB7:PCBM ternary molecules blend, at stoichiometric ratio 1:1 and 2:1:1, respectively. The ternary molecules blend active layer attracted the attention of the re- searchers because of the possibility of broadening the absorption band. The performance of the devices was investigated and found better device per- formance in binary molecules blend while low charge mobility was observed in the ternary molecules blend active layer. The highest power conversion efficiency (n) obtained were 1.6 % for P3HT:PCBM blend and 0.56 % for P3HT:PTB7:PCBM active layer. The result indicated that the charge trans- fer mechanisms in the ternary molecules blend were not favorable on the extraction and transportation of charges to the electrodes. The morpholo- gies of the films and charge transfer properties in the two media are discussed based on SEM images and electrical measurements.