染料敏化與鈣鈦礦太陽能電池之界面電荷傳遞動力學研究

Abstract

研究電子在染料敏化太陽能電池及鈣鈦礦太陽能電池內部界面之傳遞現象 有助於瞭解電池元件之缺陷進而改善電池之光電轉換效率。 在本論文中，我們設計及架設四種量測系統，瞬態光電流光電壓衰減技術、 電荷萃取技術，光致吸收光譜及瞬態吸收光譜，並介紹其工作原理、實驗方法及 數據分析。 瞬態光電流光電壓衰減技術主要量測電池元件在開路及短路狀態之電子傳 遞特性，可得知電子在太陽能電池元件中半導體電極之傳遞速率及電子電洞再結 合速率。光致吸收光譜部分，可利用其量測氧化態染料分子或氧化態電洞傳輸材 料之吸收光譜，並進一步利用瞬態吸收光譜來分析其電子傳遞速率。 我們利用上述各種技術來量測不同組成之太陽能電池元件，針對紫質染料， 釕金屬染料及有機染料方面，我們量測其電子電洞再結合速率及其二氧化鈦費米 能階高低來得知不同結構特性之染料對於電池元件的影響；針對二氧化鈦奈米結 構，我們量測不同形貌之結構其電子傳遞特性；在鈣鈦礦太陽能電池部分，我們 進行一系列量測分析來探討其電池元件內部之電子電洞傳遞機制。

This study has investigated the electron transfer behaviour of dye sensitized solar cells (DSSC) and perovskite solar cell (PSC) using a range of time-resolved and steady state techniques. The enhanced understanding of these processes was then utilized to develop unique strategies to circumvent performance limitations associated with injection or recombination, thereby improving the power conversion efficiencies of the devices. In this study, four characterization techniques have been reported, transient photocurrent and photovoltage decay measurements, charge extraction measurement, photoinduced absorption spectroscopy and transient absorption spectroscopy. This thesis provide an account of each technique about its operating principle, experimental setup and data analysis. The transient photoelectric measurements, are obtained under short-circuit and open-circuit conditions, respectively, and the electron diffusion coefficients and electron lifetimes are extracted from fitting the decay curves accordingly. For the photoinduced absorption spectroscopy, which is useful in the characterization of long-lived (> μs) non-radiative excited states and used as the first step for transient absorption measurement. As case studies for each technique, examples are given to rationalize the observed potential shift, decay coefficients of electron transport and of charge recombination in relation to the corresponding photovoltaic performance of the device. For porphyrin dyes and organic dyes, by using the transient photoelectric measurements to understand the charge recombination process and TiO2 potential shift; for TiO2 nanostructure, we measured the charge transport kinetics with different morphology TiO2. For perovskite solar cell, we used these techniques to study the charge transport kinetics of the devices.