在本研究中，我們驗證了使用光還原法來還原氧化石墨烯。在研究開始時，我們著重在如何去還原氧化石墨烯。而在光還原法的部分，我們分別添加了硫化鈉以及亞硫酸鈉(Na2S/Na2SO3)還有三乙醇胺(triethanolamine)作為還原反應溶液中的犧牲試劑。犧牲試劑的添加，提升了光還原氧化石墨烯的效果，我們也觀察過程中其還原的程度以及所需要的時間。藉由螢光光譜分析結果，可以發現在添加犧牲試劑即硫化鈉以及亞硫酸鈉還有三乙醇胺後，氧化石墨烯的放光峰會有明顯的削弱，即使兩種犧牲試劑都能使照光後的氧化石墨烯有效的發生電荷轉移，當使用硫化鈉以及亞硫酸鈉該組犧牲試劑時，還原過程中會使得氧化石墨烯或是已經部分還原的還原氧化石墨烯產生聚集的現象，因而使得後續的還原反應受到限制，而當使用三乙醇胺作為還原反應溶液中的犧牲試劑時，由於三乙醇胺能使得過氧化石墨烯在反應過程中持續分散，因而相較於使用硫化鈉以及亞硫酸鈉來的有效果。
而第二部分，我們嘗試添加還原的氧化石墨烯在以二氧化鈦(TiO2)奈米柱為基底使用氧化鋅奈米粒子(nanoparticle)與聚(3-己基噻吩)(P3HT)混參的高分子太陽能電池。在添加氧化石墨烯後，觀察由時間解析螢光光譜與阻抗分析的結果，發現添加了還原的氧化石墨烯可幫助奈米氧化物與聚(3-己基噻吩)的電荷分離效果，與此同時也降低了電子的生命週期。藉由添加還原氧化石墨烯適當的量，可得到一最佳光伏電池的效率。我們也在本研究中討論了在聚(3-己基噻吩)與還原氧化石墨烯以及氧化鋅於二氧化鈦奈米柱的能階匹配，由時間解析螢光光譜以及凱文探針力(Kelvin probe force)顯微技術的量測，可以確認電子能在吸光層中有效的從聚(3-己基噻吩)傳給還原氧化石墨烯再由還原氧化石墨烯傳到氧化鋅奈米粒子，因而能確認在氧化物混參聚(3-己基噻吩)的高分子太陽能電池中還原氧化石墨烯可以做為一輔助的電子接受者。在使用了九百奈米厚度的二氧化鈦奈米柱陣列為基底且無使用任何表面修飾劑的條件下，添加還原氧化石墨烯於氧化物混參聚(3-己基噻吩)的高分子太陽能電池可得到3.79%的效率。
鑒於發現添加還原氧化石墨烯後可提升高分子太陽能電池的效率，最後一個部分，我們嘗試添加還原氧化石墨烯於以甲基胺基鉛碘為基底的鈣鈦礦中來改善其太陽能電池的效率，而為了使還原氧化石墨烯能順利分散在有機溶劑中，首先我們對氧化石墨烯利用1-芘羧酸(1-pyrenecarboxylic acid, PCA)進行表面修飾並利用維他命c來將其還原成還原氧化石墨烯。由螢光光譜以及時間解析螢光光譜的分析結果，我們能證實經由添加1-芘羧酸修飾的還原氧化石墨烯能幫助其在鈣鈦礦層中的電荷分離效果，即證實了1-芘羧酸修飾後的還原氧化石墨烯能作為一個電子接受者來幫助電池中短路電流的提升，由電池的效率參數可發現在添加了0.5μl的1-芘羧酸修飾還原氧化石墨烯於電池中可提升27%的電流密度。

In this thesis, we demonstrated the photoreduction of graphene oxides (GOs) to obtain reduced GO (RGO). The first part, we focus on the reduction of GOs. The photoreduction of graphene oxides (GOs) was carried out in the presence of a sacrificial agent of Na2S/Na2SO3 and triethanolamine (TEA) separately in the solution. The photoreduction of GOs was enhanced with the addition of the sacrificial agent, which was examined in terms of reduction extent and needed reduction period. The quench of the GO emission was observed in the photoluminescence spectra of both GO solutions with Na2S/Na2SO3 and TEA. Although both sacrificial agents facilitated the charge transfer in the irradiated GO solutions, the aggregation of GO/reduced GO (RGO) occurred in the Na2S/Na2SO3-contained solution during photoreduction, which limited further photoreduction of GOs with the assistance of Na2S/Na2SO3. By keeping good dispersion characteristic during the whole process, the photoreduction efficiency of GO in the presence of TEA was therefore superior to that with the assistance of Na2S/Na2SO3.
Furthermore, to improve the performance of organic hybrid polymer solar cell, pristine reduced graphene oxide (RGO) sheets are added in the nanoarchitectural TiO2 nanorod (NR)-ZnO nanoparticle (NP)/P3HT hybrid polymer solar cells. The second part, we try to add RGO into polymer solar cell. With the addition of RGOs, the enhancement of the charge separation and the decrease of the electron lifetime in the nanoarchitectural metal oxide/P3HT hybrid are determined by time-resolved photoluminescence (TRPL) and impedance spectroscopy, respectively. The photovoltaic performance of the hybrid solar cell is therefore optimized by an appropriate addition of RGOs in the active layer. Moreover, intensity modulation of photocurrent spectroscopy measurements indicate that the electron transport rates in the hybrid solar cells are improved as adding RGOs in the active layer. Energy matching among P3HT, RGOs, and ZnO NPs is demonstrated in the TiO2 NR-ZnO NP/RGO/P3HT hybrid solar cell. It is respectively confirmed by TRPL and Kelvin probe force microscopy measurements that electron transfers occur effectively from P3HT to RGOs and from RGOs to ZnO NPs in the active layer. The pristine RGOs are concluded to be an energy-matched auxiliary electron acceptor in the nanoarchitectural metal-oxide/P3HT hybrid solar cell. An efficiency of 3.79% is achieved in the RGO-incorporated nanoarchitectural metal oxide/P3HT hybrid solar cell fabricated free of interfacial modification using the 900 nm-thick TiO2 NR array.
In view of the additive of RGO, it gives the improvement in polymer hybrid solar cell. The final stages, RGOs have been added into the CH3NH3PbI3-based perovskite solar cells to improve the photovoltaic performance. In order to make it possible for RGO to be dispersed in polar organic solvents, GOs were first modified with 1-pyrenecarboxylic acid (PCA) and reduced using vitamin C. Both PL and TRPL evidence the efficient charge separation as the existence of PCA-RGO into perovskite layer. It confirm that PCA-RGO can sever as an electron acceptor into perovskite to enhance the short-circuit photocurrent. The short-circuit photocurrent density exhibited a 27% enhancement with the addition of 0.5 μl PCA-RGOs into the cells.

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