仿生太陽能電池元件及其光電能量轉換機制研究---總計畫(I)

Abstract

人類能源需求於 2050 年時將倍增、於2100 年時將成長3 倍、而現有能源將日趨短缺。 未來新能源之獲得將以豐富且乾淨之太陽輻射為最終來源。但如何開發具有可微調其電子能帶 之太陽能轉能材料為人類社會未來之重要挑戰之一。其中、解決之道之一為開發具高效率分子 層級能階轉換之仿光合作用系統以作為太陽能轉能之應用。 本計畫之最終目標為開發一熱穩定且可有效進行光電能量轉換之仿光合作用(光激發/電 荷分離/電子轉移等反應)於一體之單一金屬蛋白質複合物或複合物陣列(仿生光催化系統)。另 外、瞭解此仿生光催化系統之能量吸收及轉換過程中之能階分佈及電子轉移動力學為一重要之 基礎課題。因此，我們提出三個相互關聯之子計畫，經由跨領域整合研究以開發此一仿生光催 化系統，並研究其能階分佈與能量轉換機制。在子計畫一我們將設計及合成含各式金屬之不同 紫質及其衍生物為基礎之供給-接受體系統，以提供作為子計畫二及三之人造蛋白質重組及其 相關之太陽光電與基礎動力學研究。子計畫二則將以脫輔基肌紅蛋白為模板進行蛋白質工程之 改造，以將其轉化成為具有各種不同能帶調控或氧化-還原態及電子轉移能力之金屬蛋白、並 將其與子計畫一之不同紫質及其衍生物為基礎之供給-接受體系統進行重組，及應用於光電能 量轉換與反應機制之研究。第三子計畫則將利用第一級第二子計畫所提供之分子材料製成仿生 太陽能電池元件並量測其光電轉換效率，同時利用皮秒及飛秒之時間解析光譜技術以探索此一 能量轉化過程之基礎動力學機制。

The needs of the planet for the energy will double and triple by mid-century and the end of century, respectively, with the fossil fuels that can no longer furnish. Solar radiation is a plentiful, clean, and ultimate source of power. However, how to develop new materials with the ability to tune the electronic bandgap for maximal solar energy conversion efficiency becomes one of society』s important challenges. One route to the solution is the development of bio-mimetic photosynthetic system with diverse bandgap properties and high energy conversion efficiency at the molecular level. The ultimate goal of this proposal aims at developing an integrated bio-mimetic photosynthetic system, single artificial protein complex or protein complex array with integrated photoinduced charge separation and electron transfer properties, which enables thermal stability and efficient photovoltaic conversion of solar energy into electricity. In parallel, understanding of the distributions in energy levels and electron transfer dynamics of the bio-mimetic system is of fundamental importance and prerequisite for efficient energy absorption and photovoltaic conversion. Therefore, we propose herein with three inter-connected subprojects to develop the bio-mimetic photosynthetic systems and to study the reaction mechanisms as well as electron/energy transfer dynamics, with the integration of multidisciplinary research fields. In subproject 1, we propose to design and synthesize various metallo-porphyrin-based donor-acceptor systems as prosthetic group, which will be reconstituted into engineered artificial protein to form complexes for photovoltaic applications and for fundamental studies described in subproject 2 and 3. In subproject 2, artificial proteins with different oxidation states or redox potential for bandgap adjustment will be designed and constructed, using apomyoglobin as a model template, and subjected to prosthetic group reconstitution and bio-mimetic photovoltaic applications and for interfacial electron transfer dynamics and reaction mechanism studies. In subproject 3, the bio-mimetic solar cell device will be fabricated and characterized; the fundamental process controlling the important photovoltaic energy conversion functions will be probed with the state-of-the-art spectroscopic technology - femtosecond time-resolved spectroscopy.