使用兩性界面活性劑提升聚(3-庚酸噻吩)電洞傳導層建構之反式鈣鈦礦太陽能電池的光伏特徵與長效穩定性

Abstract

本研究以MA0.16Cs0.05FA0.79Pb(I0.9Br0.1)3結構作為鈣鈦礦主動層，分別引入椰油醯胺丙基甜菜鹼 (Cocamidopropyl betaine, CAPB) 及月桂基甜菜鹼 (Lauryl betaine, LB) 兩性離子界面活性劑，修飾鈣鈦礦晶體及界面性質，並製備p-i-n反式鈣鈦礦太陽能電池元件，以提升太陽能電池元件之效率及長效穩定性。傅立葉轉換紅外光譜 (FTIR) 及X射線光電子能譜儀 (XPS) 實驗數據證明，CAPB及LB之羧酸極性基團與鈣鈦礦形成配位作用力，故能有效鈍化鈣鈦礦晶體缺陷，抑制非輻射電荷再結合發生。此外，表面能計算及電化學阻抗分析證實，添加0.2 wt% CAPB及0.2 wt% LB可以減少鈣鈦礦及PC61BM之間的界面缺陷，並提升兩層之間的相容性。因此，以0.2 wt% CAPB以及0.2 wt% LB添加至鈣鈦礦層中，其元件最高效率由18.80%分別提升至21.47%及22.24%。 ITO/ P3HT-COOH/ Perovskite樣品的EDX剖面分析證實，CAPB及LB在鈣鈦礦膜表面，可自組裝形成一碳鏈朝外的分子膜層，因此它的水滴接觸角由純鈣鈦礦的59.80 °分別提升至70.84 °及75.75 °，降低外界水氣的侵入。因此，在相對濕度50%及室溫 (25 °C) 環境下，0.2 wt% CAPB元件經過4080小時存放後，仍保持起始效率之98.3%；0.2 wt% LB元件經過3888小時後，亦可維持在起始效率之91.2%。在熱穩定性方面，無添加劑元件在氮氣及65°C、85 °C環境下分別儲放792小時與528小時後，其效率即下降至原始數值的80%；0.2 wt% CAPB元件在65 °C和85 °C分別經過1872小時後，效率仍可維持在93.5%和80.8%；而0.2 wt% LB元件則分別保持在90.2%和63.6%。光穩定性係在室溫及充滿氮氣的環境，以AM1.5G模擬光源(100 mW/cm2光強)連續照射下進行測試。0.2 wt% CAPB以及0.2 wt% LB元件經過48小時照光後，它們的元件效能分別下降至起始效率之88.0%及78.5%；無添加劑元件經過36小時的照光後則僅能維持71.9%之起始效率。

In this study, inverted p-i-n perovskite solar cells were fabricated using MA0.16Cs0.05FA0.79Pb(I0.9Br0.1)3 as the photoactive layer, and cocamidopropyl betaine (CAPB) and lauryl betaine (LB) as the additive. The effect of these zwitterionic surfactants on the quality of perovskite layer, and the photovoltaic performance and long-term stability of solar devices were extensively investigated. The results from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy revealed that the carboxylic acid groups can interact with the Pb in perovskite that effectively passivate the surface defects of perovskite crystals, reducing the nonradiative charge recombination. In addition, the surface energy calculation and electrochemical impedance analysis confirmed that the presence of CAPB (0.2 wt%) and LB (0.2 wt%) can reduce the interface defects between the perovskite and PC61BM and improve the compatibility between the two layers. Therefore, the incorporation of 0.2 wt% CAPB and 0.2 wt% LB to the perovskite film substantially increased the power conversion efficiencies (PCEs) of the champion cells from 18.80% to 21.47% and 22.24%, respectively. The EDX longitudinal profile analysis of the ITO/P3HT-COOH/perovskite samples showed that CAPB and LB can self-assemble on the top surface of the perovskite film to form a molecular layer with hydrocarbon chains facing outward. Therefore, the contact angle increased from 59.80° for the pristine perovskite film to 70.84° and 75.75° for the CAPB:perovskite and LB:perovskite films, respectively. Under a relative humidity of 50% and room temperature (25 °C), the CAPB device still maintained 98.3% of its initial PCE after 4080 hours of storage; the LB device retained 91.2% of its initial PCE after 3888 hours. In terms of thermal stability, the PCE of the control device dropped to 80% of the original value after being stored at 65°C and 85°C in nitrogen atmosphere for 792 hours and 528 hours, respectively. After aging at 65°C and 85°C for 1872 hours, the CAPB devices maintained 93.5% and 80.8%; the LB devices remained 90.2% and 63.6% of their initial PCEs, respectively. The photostability experiments were conducted in a nitrogen-filled environment at room temperature and the devices were continuously illuminated with an AM1.5G simulated light source at an intensity of 100 mW/cm2. After 48 hours of illumination, the PCEs of the CAPB and LB devices degraded to 88.0% and 78.5% of the initial values, respectively; the control device could only maintain 71.9% of its initial PCE after 36 hours of illumination.