| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 93 === In this thesis, the charge separation and transport efficiency of inorganic/organic hybrid photovoltaic material were studied. The unique quantum confinement and shape manipulation characteristic for nanoparticle can be utilized to fabricate photovoltaic device with special physical properties not observed in traditional silicon-base inorganic cell.
Initial studies include optical properties of pristine MEH-PPV conducting polymer. Variation of the polymer concentration and molecular weight show that the PL and absorption spectrum red-shift with high solution concentration and high molecular weight. Exciton decay time is also influenced by interchain interaction. The interchain interaction could result in energy transfer and PL quench.
We also study temperature dependence of blend system in dynamic and static measurements. The experiments show that at same temperature, PL spectra have red shift as the CdSe nanoparticle concentration increase in the polymer matrix. At low temperature, the absorption and PL spectrum also shift to long wavelength. These results can explain that the stacking order increase at low temperature and the increase in CdSe nanoparticle concentration also have similar effect. These phenomenons are interpreted by the increase in effective conjugated length. Effective conjugated length decreases while the temperature increases due to chain torsional motion. Therefore, increase in CdSe nanoparticle concentration would extend the effective conjugated length, and result in different Vibronic level transition decay time.
Thin films photovoltaic device with varied CdSe nanoparticle concentration have significant improvement over pristine MEH-PPV device. This is consistent with charge separation efficiency improvement at high nanoparticle concentration. High nanoparticle concentration not only provides charge separation pathway, but also support efficiency electron transfer route. Also the short circuit current is proportional to CdSe concentration.
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