本研究藉由改變PPV側鏈的化學結構，測量在溶液態及固態的UV-Vis吸收光譜、光激發光光譜以及時間解析光激發光光譜，並藉由Strickler-Berg equation計算激子固有生命期，探討化學結構對於激子生命期、激子固有生命期與光激發光量子效率的影響。另外，製作二極體元件測量電流-電壓特性，由空間電荷限制電流模型計算出電洞遷移率，並以歐姆接觸關係式計算出平衡電洞濃度。藉由Fowler-Nordheim equation結合元件電流-電壓特性，預測在不同能障高度的載子再結合效率，探討化學結構對於載子特性及載子再結合效率的影響，並進一步預測元件外部量子效率。
溶液態UV-Vis吸收光譜中顯示隨著溶劑極性增加，極性最小的DO-PPV最大吸收波長有藍位移情形，顯示其共軛長度隨著溶劑極性增加而減少。其他兩高分子的最大吸收波長則沒有改變。溶液態光激發光光譜中顯示隨著溶劑極性的增加，極性最小的DO-PPV最大發射波長有些許的藍位移情形，其他兩高分子的最大發射波長則有些許的紅位移情形。相對於溶液態，固態光激發光光譜的發射波長有紅位移情形，比較位移量得知π-π stacking interaction最大的是DO-PPV，最小的是MEH-PPV。
比較溶液態的激子固有生命期，得知極性越小的高分子其激子固有生命期越短，這是由於在吸收過程中存在較高的分子內電子轉移機率。比較固態激子固有生命期，顯示其趨勢與溶液態激子固有生命期相同，但相對於溶液態，固態激子固有生命期較短。此外，比較三個高分子的激子生命期，顯示π-π stacking interaction越大的高分子其激子生命期越短。相對於溶液態，固態激子生命期較短，這是由於在固態時π-π stacking interaction較溶液態大。
比較溶液態及固態的光激發光量子效率，顯示激子固有生命期越短的高分子其光激發光量子效率越高。相對於溶液態，固態光激發光量子效率較低。
比較三個高分子相同電場下的電洞遷移率及平衡電洞濃度，發現DO-PPV的電洞遷移率最高， MO-PPV最低，而能隙值越高的高分子其平衡電洞濃度越低。
由載子再結合效率預測結果得知，隨著能障高度的提高，在相同電壓下的載子再結合效率下降，元件起始電壓提高。此外，比較外部量子效率的預測值，顯示在本研究中固態光激發光量子效率較高的高分子其外部量子效率亦較高。

This study investigated the influence of PPV side chain structures on the exciton lifetime, exciton intrinsic lifetime, and photoluminescence efficiency by measuring the UV-Vis absorption spectra, photoluminescence spectra, time-resolved photoluminescence spectra, and calculating the exciton intrinsic lifetime by Strickler-Berg equation. On the other hand, by fabricating the LED devices and measuring current-voltage characteristics, current-voltage characteristics were used to calculate the hole mobility and equilibrium hole concentration by the space charge limited current model and ohmic contact relationship. By combining Fowler-Nordheim equation and current-voltage characteristics, the carrier recombination efficiency with various barrier heights could be predicted. Carrier properties and the carrier recombination efficiency for different polymers were further investigated. Moreover, the external quantum efficiency was predicted.
In UV-Vis absorption spectra, the maximum absorption wavelength of DO-PPV showed blue shift with increasing the solvent polarity, while the maximum absorption wavelength of the other two polymers were independent of the solvent polarity in solution state. In photoluminescence spectra, the maximum emission wavelength of DO-PPV showed blue shift with increasing the solvent polarity, while the maximum emission wavelength of the other two polymers showed red shift with increasing the solvent polarity in solution state. Compared to the photoluminescence spectra in solution state, the emission wavelength of photoluminescence spectra in solid state showed red shift. By comparing the results of the shift displacement, it was found that DO-PPV had the strongest π-π stacking interaction, follow by MO-PPV, and then MEH-PPV.
By comparing the exciton intrinsic lifetime in solution state with different polymers, it was found that the polymers with smaller polarity had shorter exciton intrinsic lifetime, and it was due to higher electronic transition probability of the absorption band. By comparing the exciton intrinsic lifetime in solid state with different polymers, the trend of characteristics was similar to solution state, except polymers in solid state had shorter exciton intrinsic lifetime. Besides, the polymers with stronger π-π stacking interaction had shorter exciton lifetime. The exciton lifetime was relative shorter in solid state compared to solution state, and it was due to the stronger π-π stacking interaction in solid state.
By comparing the photoluminescence efficiency in solution and solid states with different polymers, it was found that the polymers with shorter exciton intrinsic lifetime had higher photoluminescence efficiency. Furthermore, the photoluminescence efficiency was relative smaller in solid state compared to solution state.
By comparing the hole mobility and equilibrium hole concentration at the same electric field with different polymers, it was found that DO-PPV had the highest hole mobility, follow by MEH-PPV, and then MO-PPV. Besides, the polymers with higher energy gap had smaller equilibrium hole concentration.
From the predicted carrier recombination efficiency results, it was found that the carrier recombination efficiency was decreased and the turn-on voltage was increased with increasing the barrier height. Besides, by comparing the external quantum efficiency with different polymers, it was also found that polymers with higher photoluminescence efficiency in solid state also had higher external quantum efficiency in this study.

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