| 摘要註: |
目前有機太陽能電池因其具有可大面積製作、具撓曲性、低成本等特點已被密集的進行研究，但有機太陽能電池的效率受限於高分子給體與有機受體的低載子移動率。使用高電子移動性無機奈米晶體做為電子受體並引入共軛高分子中以製造本體異質結(bulk heterojunction)之太陽能電池元件，形成之高分子/無機奈米晶體太陽能電池即可部份克服電子傳輸限制之問題。但是，應用這些奈米複材於太陽能電池時，需要奈米晶體在高分子給體中具有好的分散性，創造高分子與奈米晶體間之較大接面面積，以進行高效率之電子轉移。為了達到較高的分散性，本論文將在無機奈米晶體硒化鎘(cadmium selenide, CdSe)上，接上有機高分子聚乙烯咔唑 (poly(N-vinylcarbazole), PVK)以增加其與高分子給體相之相容性。本論文分成三部份，第一部分為合成太陽能電池元件構造層材料：電洞傳輸層(hole transport layer, HTL)材料聚二苯胺 (poly(diphenylamine), PDPA)及聚三苯胺 (poly(triphenylamine), PTPA)，活化層(ative layer)材料聚9,9-二辛基芴 (poly(9,9-dioctylfluorenyl-2,7-diyl), PFO)、聚2-甲氧基-5-(2’-乙基-己氧基)-1,4-苯乙烯 (poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene], MEH-PPV)、聚乙烯咔唑及有機無機奈米複合材料CdSe-PVK，與光學阻隔層(optical spacer)材料TiOx。本論文中使用Yamamoto法合成出PDPA及PFO，以Kumada法合成PTPA，而MEH-PPV則透過Gilch法製備，PVK及CdSe-PVK利用原子轉移自由基聚合法(Atom transfer radical polymerization, ATRP)得到，光學阻隔層材料TiOx則是以溶膠-凝膠法(sol-gel)合成。第二部分利用紅外線光譜分析（FT-IR）、核磁共振光譜（1H-NMR）及X射線繞射圖 (XRD)鑑定光電材料皆合成成功，凝膠滲透層析 (GPC)測得光電高分子材料之分子量及其聚合分佈指數值(PDI)，以紫外-可見光光譜 (UV-Vis)及螢光光譜 (PL)觀察光電材料之光學性質及能隙後，可由循環伏安圖譜(CV)估算出光電材料之最高滿軌域(HOMO)能量及最低空軌域(LUMO)能量，熱重分析儀(TGA)及熱示差掃瞄卡計(DSC)可分析出材料之熱穩定性質，並以穿透式電子顯微鏡(TEM)及掃描式電子顯微鏡(SEM)觀察出光電材料之型態。第三部分使用上述合成的光電材料應用於高分子本體異質結太陽能電池元件，並進行光電轉換效率的量測，得到下述結果：以ITO/HTL/P3HT:PCBM/Al為元件構造，使用PDPA:DBSA及PTPA:DBSA當作電洞傳輸層材料，量測其元件特性曲線後發現使用PDPA:DBSA及PTPA:DBSA之元件效率分別為2.02 %及1.15 %。以ITO/PEDOT:PSS/P3HT:CdSe-PVK/Al為元件構造，以紫外-可見光光譜、螢光光譜、原子力顯微鏡(AFM)及穿透式電子顯微鏡觀察活化層在不同退火溫度及時間下之特徵及相分離型態，並量測其元件光電轉換效率，發現當退火條件為150℃, 30 min時，有最高光電轉換效率0.059 %。以ITO/PEDOT:PSS/P3HT:CdSe-PVK/Al為元件構造，發現當退火條件為150℃, 30 min時，添加1,8-辛二硫醇(1,8-octanedithiol, OT)至主要溶劑鄰二氯苯(o-dichlorobenzene, DCB)中，其光電轉換效率可提升至0.085 %。以ITO/PEDOT:PSS/P3HT:PCBM/optical spacer layer/Al作為元件構造，發現以TiO2及TiOx作為optical spacer layer材料之光電轉換效率分別為2.12 %及2.53%，皆高於未添加optical spacer layer之元件效率1.99%。 Organic solar cells (OSCs) have attracted strong interest in recent years due to their advantages of low cost, light weight, and capability to fabricate large area and flexible devices. However, the power conversion efficiency (PCE) of OSCs requires a significant improvement of carrier mobility of polymer donors and organic acceptors in the active layer. Bulk heterojunction solar cell device fabricated by high mobility nanocrystal electron acceptor and conjugated polymer donor might overcome the electron transportation problem. However, application of this kind of nanocomposite in solar cell needs the good dispersion of nanocrystal in the polymer matrix. A large contact area between donor and acceptor enhance the high efficiency of electron transfer. To attain this goal, our approach was to attach a short chain of poly(N-vinylcarbazole) (PVK) to increase the compatibility of both phase. Our research was proceeded in three sequences. The first step was to synthesize the materials of constituted layers including (1) hole transporting layer: poly(diphenylamine) (PDPA) and poly(triphenylamine) (PTPA); (2) active layer: poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), PVK and inorganic/organic composite CdSe-PVK; (3) optical spacer: TiOx. For the synthesis of these materials, PDPA and PFO were carried out by Yamamoto approach; PTPA was performed with Kumada coupling; MEH-PPV was prepared by Gilch technique. PVK and CdSe-PVK were obtained by atom transfer radical polymerization (ATRP). As for the TiOx for optical spacer layer, it was prepared by sol-gel method.All synthesized optoelectronic materials were confirmed with FTIR, 1H NMR and XRD analyses. Molecular weights and polydispersity indices were obtained by GPC. Optical properties were observed with UV-Vis and PL. On the other hand, by the combination of using bandgap value from UV-Vis spectroscopies together with the oxidation-reduction potential values from cyclic voltammetry, HOMO and LUMO values of all optoelectronic materials could be estimated. In addition, thermal properties of all synthesized materials could be analyzed by DSC and TGA. TEM and SEM analyses were also carried out to investigate the morphologies of all materials.The third step was the application of all of the synthesized materials in the constituted layers of polymer bulk heterojunction solar cells and the measurements of power conversion efficiency. The results are as follows:Based on the ITO/HTL/P3HT:PCBM/Al device structure, when PDPA:DBSA and PTPA:DBSA were used as HTL materials and characteristic curves were measured, it was found the PCE values for PDPA:DBSA and PTPA:DBSA were 2.02% and 1.15%, respectively.Based on the ITO/PEDOT:PSS/P3HT:CdSe-PVK/Al device structure, the morphologies of phase separation in the active layer under different thermal annealing conditions were investigated and observed by UV-Vis, PL, AFM and TEM. After measuring PCE values, it was concluded that the highest PCE 0.059% could be acquired under the annealing condition at 150℃ for 30 mins.Based on the ITO/PEDOT:PSS/P3HT:CdSe-PVK/Al device structure, the solvent effect was also investigated. The results showed that only 1% 1,8-octanedithiol added to major solvent o-dichlorobenzene could increase the PCE value to 0.085% when the annealing condition was 150℃ for 30 mins.Based on the ITO/PEDOT:PSS/P3HT:CdSe-PVK/optical spacer/Al device structure, the optical spacer TiOx and TiO2 were employed and their PCE value were measured. It was found that PCE value of 2.12% and 2.53% were obtained for TiOx and TiO2, respectively, higher than 1.99% value of the unemployed one. |