我們比較研究大氣噴射電漿與爐管鍛燒製成所製作之鉑奈米粒子點綴石墨烯對電極染料敏化太陽能電池(DSSC, dye-sensitized solar cell)。首先網印含氯鉑酸之石墨烯漿料於氟摻雜氧化錫(FTO, fluorine-doped tin oxide) 玻璃上後分別利用爐管及大氣噴射電漿進行退火,並比較兩者製程所製作之對電極及所組裝之染料敏化太陽能電池。大氣電漿下的基板溫度及爐管溫度均控制在510 °C。爐管鍛燒與大氣電漿鍛燒鍛燒之試片均能觀察到鉑奈米粒子附於石墨烯片狀結構上,提供了 DSSC 對電極需要的 I3-還原反應催化能力。而由阻抗頻譜分析、Tafel曲線量測、元件效率量測發現爐管鍛燒1.5分鐘之對電極有最好的電化學活性。大氣電漿鍛燒鍛燒之石墨烯/鉑對電極可以在較短時間內改善元件效率,而爐管鍛燒石墨烯/鉑對電極在短時間內無法有效完全移除對電極內的有機物,因此太陽能電池效率較大氣電漿鍛燒的試片來得低。但較長處理時間的條件下,爐管鍛燒顯現出較佳的太陽能電池效率。主要原因在氮氣大氣電漿的高反應粒子在較高溫的環境下(510 °C)與碳材反應劇烈,因此在短時間內就會將石墨烯反應(氧化/汽化)完畢。但爐管鍛燒對石墨烯的反應較溫和,因此爐管鍛燒需要較長的時間,而石墨烯也可以在爐管環境中存在較長的時間。本研究所進行的電化學阻抗頻譜分析、Tafel曲線量測、太陽能電池元件特性分析顯示一致的結果,較低的電荷傳輸電阻(charge transfer resistance)有較高的催化活性面積(active area),及有較高的交換電流密度(exchange current density),表示對電極催化活性較好,因而有較高的填充因子及太陽能電池效率。
We comparatively investigate dye-sensitized solar cells (DSSCs) with Pt-decorated reduced graphene oxides (rGOs) counter electrodes calcined by furnace and atmospheric-pressure plasma jet (APPJ). Pastes that contain chloroplatinic acid solution, rGOs, ethyl cellulose, and terpineol are first screen-printed onto fluorine-doped tin oxide (FTO) glass substrate and then calcined by furnace or nitrogen APPJ. The substrate temperature is set to 510 °C in both cases. Pt nanodots are well distributed on the rGO nanoflakes after furnace or APPJ calcination. Both rGO and Pt can enhance the catalytic effect for reducing I3− to I−.A nitrogen APPJ interacts vigorously with carbonaceous materials in the pastes to enhance DSSC efficiency with a shorter processing time. However, prolonged APPJ-calcination can damage/oxidize rGOs; therefore, for longer processing times, furnace-calcination in turn achieves better DSSC performance. These results agree well with those of electrochemical impedance spectroscopy (EIS) and Tafel experiments.