染料敏化與鈣鈦礦太陽能電池的載子緩解動力學

Abstract

於本論文中，將藉由飛秒瞬態吸收光譜系統、電致螢光光譜系統與飛秒螢光衰減光譜系統了解染料敏化太陽能電池與鈣鈦礦太陽能電池之電子與激子的傳遞與緩解機制。 首先，藉由飛秒紅外光瞬態吸收光譜系統，討論含有苯並咪唑取代基之釕錯合物染料 (RD5、RD12、RD15 – RD18) 吸附於二氧化鈦半導體表面之介面電子傳遞動力學，藉由二能階模型擬和可以得到此系統間跨越的速率受釕錯合物之氟取代基與噻吩取代基的數量增加而減緩。 第二部分為藉由電致螢光光譜了解鋅紫質染料的電荷分離程度。於本實驗中量測三種高效率之鋅紫質染料 (YD2、YD2-oC8 與YD30) 吸附於二氧化鈦表面或混參於 PMMA 之電致螢光光譜。於兩種薄膜系統中，均可觀察到具推拉電子基之 YD2 與 YD2-oC8 的螢光受外加電場影響而淬息，但無推電子取代基之 YD30 則有螢光增強的現象。此淬息現象應為染料之電荷分離態受電場影響而穩定後，激發態之電子可傳遞之電荷分離態進而注入二氧化鈦之導帶；相對而言，無推電子取代基之YD30 的電荷分離程度較差，即使外加電場仍舊無法將激發態電子傳遞之電荷分離態，且外加電場可有效減緩非放光途徑之緩解，而有螢光增強之現象。 第三部分為鈣鈦礦之激子緩解動力學。於此，藉由飛秒螢光上轉移光閘系統量測鈣鈦礦於氧化鋁或氧化鎳表面，藉由複合之連續動力學模型解析鈣鈦礦之 670 – 810 nm 的時間解析螢光光譜，於所有偵測波長均可擬和得到一高能態與二低能態之緩解過程。而藉由氧化鋁與氧化鎳之比較，可以得知鈣鈦礦與氧化鎳間之電洞傳輸生命期約為五奈秒，此傳輸速率仍快於其他緩解途徑，而具有極高之光電轉換效率。

Femtosecond infrared transient absorption spectral technique (IRTA), electrophotoluminescence measurement (E-PL), and femtosecond photoluminescence optical gating system (FOG) were used to investigate the electron transfer dynamics for dye-sensitized solar cells and perovskite based thin film solar cells. By means of IRTA, interfacial electron transfer dynamics for a series of benzimidazole-based heteroleptic ruthenium dyes sensitized on TiO2 thin films. Ru dyes substituted with fluorine atoms and/or thiophene units in the benzimidazole ligands showed an effect to retard the 3MLCT electron injection compared to that of the non-substituted dye. Porphyrin sensitizers either sensitized on TiO2 films or embedded in PMMA films were investigated using E-PL spectra. A non-fluorescent state with charge separation is proposed to be involved in push-pull systems so that the electron injection becomes accelerated in the presence of a strong electric field. The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO were investigated with FOG. The temporal profiles of emission were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations.