| Summary: | 碩士 === 國立中央大學 === 物理學系 === 103 === The thesis is research of Organic Photovoltaic cell (OPV) of high molecular material. OPV is mainly consist of organic semiconductor. When the organic semiconductor can absorb above 90% solar power, the thickness of it needs at least 100~200 nm. But the diffusion length of exciton which is produced by organic semiconductor which absorb solar power is only 10~20 nm. Only if the exciton contact the interface between donor and acceptor of OPV in diffusion process, the exciton will efficiently separate into the hole and electron due to difference of chemical potential. The hole and electron respectively conduct through donor and acceptor to electrode to produce electricity. Hence it is an important issue that contact area between donor and acceptor influences efficiency of OPV.
In the thesis, we used matrix assisted pulse laser evaporation(MAPLE) to fabricate the active layer of OPV. The materials of active layer were poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl-C61-butyric acid Methyl ester(PCBM). We produced the film composed of P3HT nanoparticle with MAPLE and backfilled gas technique in order to increase porosity of the film. Then we made PCBM fill in P3HT film nanopores with MAPLE to increase the contact area between P3HT(donor) and PCBM(acceptor) and enhance the efficiency of OPV. We also tried to dissolve P3HT and PCBM in the same solvent(ortho-xylene) to made target in MAPLE with cooling system, and we produced the bulk heterojunction OPV with MAPLE to increase the contact area between P3HT and PCBM and enhance the efficiency of OPV. We also made P3HT and PCBM produce phase segregation with MAPLE and backfilled gas technique in order to achieve the effect of solvent annealing in conventional process.
According to the result, we found the nanostructured OPV efficiency is half times higher than the bilayer one, and the thermal annealing bulk heterojunction OPV efficiency is twice higher than the nanostructured one. However, we guessed the reason of low current is there are many defects in film and lead to increase possibility of recombination in MAPLE process.
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