奈米銀氧化石墨烯對高分子太陽能電池光電轉換效率的影響

Effect of Graphene Oxide/Ag Nanoparticles on the Efficiency of Polymer Solar Cells

我們採用改良式Hummer法製備之氧化石墨作為氧化石墨烯（graphene oxide, GO）之前驅物，以硝酸銀（AgNO3）作為奈米銀粒子前驅物，以檸檬酸鈉做為還原劑合成三種奈米銀氧化石墨烯（GOAg），分別命名為GOAg-1、GOAg-2與GOAg-3。我們將奈米銀石墨烯以濃度1.5mg／ml分散於N-methyl pyrrolidone（NMP）中，塗佈插層於PEDOT：PSS電動傳輸層與P3HT：PCBM組成的主動層間來製備高分子太陽能電池，研究奈米銀氧化石墨烯對高分子太陽電池光電特性之影響。本研究之太陽能電池元件結構為Glass／ITO／PEDOT：PSS／GOAg／P3HT：PCPDTBT：PC61BM／Ca／Al，我們利用紫外光-可見光吸收光譜儀（UV-Vis）、掃描探針顯微鏡（SPM）、場發射電子顯微鏡（FESEM）和太陽光模擬光源系統，來測量吸收度、粗糙度、表面形態和光電性質。由結果得知，插層這三種GOAg之高分子太陽能電池之短路電流密度（short circuit current density, Jsc）、填充因子（fill factor, FF）與光電轉換效率（power conversion efficiency, PCE％）皆比未含奈米銀氧化石墨烯之電池高，顯示插層這三種GOAg於電動傳輸層與主動層間皆能有效提高電池之光電性質。三種GOAg中以GOAg-2具最佳提升效果，因為此電池具有最高的短路電流密度與光電轉換效率，分別為9.71mA／cm2與4.02％，與未含奈米銀氧化石墨烯之電池比較分別提升了36.4％與80.3％，此結果可能是由於石墨烯具有高電子遷移率，因此提升了高分子太陽能電池之光電性質。

Graphene oxide / Ag nanoparticles (GOAg) were fabricated via a facile method, employing graphite oxide as a precursor of graphene oxide (GO), AgNO3 as a precursor of Ag nanoparticles, and sodium citrate as a reducing and stabilizing agent. We synthesized three kinds of GOAg as GOAg-1, GOAg-2 and GOAg-3. We investigated the effect of incorporating GOAg between the hole transfer layer (HTL) of poly (ethylene dioxythiophene) (PEDOT)-polystyrene sulfonic acid (PSS) (PEDOT : PSS) and active layer (P3HT:PCBM = 1:1 weight ratio) on the photovoltaic performance. The cell structure was Glass / ITO / PEDOT : PSS / GOAg / P3HT : PCBM / Ca / Al. The concentration of GOAg solution was 1.5 mg/ml in N-methyl pyrrolidone (NMP) solvent and the GOAg layer was coated on the HTL layer by spincoating. We used the UV-Vis, SPM, FE-SEM and solar simulator to measure the absorbance, roughness, surface morphology, and power conversion efficiency (PCE), respectively. From these results, we found that the short circuit current density (Jsc), fill factor (FF) and PCE of the cells with GOAg are always higher than those of cell without GOAg. The cell with GOAg- 2 has the highest short circuit current density 9.71 mA/cm2, an increase of 36.4%, and the highest power conversion efficiency 4.02%, an increase of 80.3%. These improvements are due to the high carrier mobility of graphene.