| 摘要: | 近年來鈣鈦礦太陽能電池(Perovskite Solar Cells, PSCs)因光電轉換效率(PCE)高且使用材料少而快速發展。在一般式鉛鈣鈦礦太陽能電池中常使用具有電子傳遞能力的SnO2膜作為電子傳遞層ETL，以市售SnO2膠體溶液(簡稱CT溶液)來製備ETL最為常見，但CT溶液存放一個月後會產生明顯的聚集現象，導致所組裝元件的效率降低，且市售CT溶液可能某些原因無法取得，而其他製備SnO2膠體溶液與ETL的方法往往需要較長的反應時間(6小時)、較高的溫度(180°C)或是較為複雜的步驟(原子層沉積法)。因此本研究以SnCl2·2H2O、H2O2與Urea反應30分鐘配製成小粒徑的SnO2膠體溶液(簡稱SC溶液)再用旋轉塗佈製成膜(SC膜)。由兩種膜的SEM形貌圖，發現SC膜較緻密，但XRD數據顯示鈣鈦礦沉積於SC膜上會有較強的δ相訊號(1.81 a.u.) (CT膜為0.92 a.u.)並有額外的PbI2繞射峰。這是因為SC膜表面有殘留物SnCl2或是中間產物SnOH2導致SC膜偏酸性，進而影響鈣鈦礦的結晶過程與結晶相的轉變。因此對SC膜進行超音波震盪清洗改變SC膜的酸鹼性，避免在製備鈣鈦層時產生δ相訊號。接著，增加鈣鈦礦前驅溶液中FAI量，以降低PbI2繞射峰強度。接著在SC溶液中加入具有銨基與氰基的分子GuSCN (SCG溶液)。XPS能譜圖得知以SCG溶液所製膜(SCG膜)有較小的氧缺陷比例最小。沉積於三種膜上鈣鈦礦的PL顯示，SCG膜萃取與傳遞電子的能力較好。以三種膜(CT膜、SC膜、與SCG膜)作為電子傳遞層所組裝元件的光電轉換效率分別20.65%, 22.40%與22.84%。最後以CT膜或SC膜作為電子傳遞層所組裝一般式元件在未封裝且放置在氮氣手套箱中，經2880小時後，效率分別維持原始效率的73%與89%，在相同測試環境下，以SCG膜作為電子傳遞層所組裝的元件經過1440小時仍維持原始效率的97%。;Perovskite Solar Cells (PSCs) have been rapidly developed due to their high power conversion efficiency (PCE) and low material used. In conventional (regular) type lead-based PSCs, SnO2 films are commonly used as the electron transport layer (ETL) due to its high electron transport ability. The most common method for preparing SnO2 ETLs uses commercial SnO2 colloidal solutions (referred to as CT solution). However, CT solution shows significant aggregation after one month of storage, leading to a decrease in PCE of the corresponding solar cell. Furthermore, CT solution may be difficult to obtain because of various reasons. Other methods for preparing SnO2 colloidal solutions and ETLs often require longer reaction times (6 hours), higher temperatures (180°C), or more complex procedures (e.g., atomic layer deposition). Therefore, this study was focus on preparing a small-particle-sized SnO2 colloidal solution (referred to as SC solution) by fixing SnCl2·2H2O, H2O2, and Urea for 30 minutes, and then spin coating the colloid solution to form films (SC films). SEM images revealed that the SC film was denser than CT film. However, XRD data showed a stronger δ-phase signal (1.81 a.u.) when perovskite was deposited on the SC film (compared to 0.92 a.u. for that coated on the CT film), along with additional PbI2 diffraction peaks. This is due to residual (SnCl2) or intermediate product (SnOH2) exists in the SC film, which affects the perovskite crystallization process and crystalline phase. To address this issue, the SC films were sonicated in H2O to reduce the residual or the intermediate product to prevent the formation of the δ-phase when perovskite deposited on it. The amount of formamidinium iodide (FAI) in the perovskite precursor solution was increased to reduce the existing of PbI2 in perovskite film. Furthermore, guanidinium thiocyanate (GuSCN), a molecule with amino and cyano groups, was added to the SC solution (forming SCG solution). XPS analysis of films prepared with the SCG solution (SCG films) showed a lower proportion of oxygen vacancies compared to that made without GSCN additive. PL data of perovskite films deposited on the three types of films (CT, SC, and SCG) show that the SCG film exhibited better electron extraction and transporting capabilities. PCE of devices assembled with the three types of ETLs (CT, SC, and SCG films) were 20.65%, 22.40%, and 22.84%, respectively. Unencapsulated devices assembled with CT or SC films as ETLs maintained 73% and 89% of their initial efficiency after 2880 hours in a nitrogen glovebox. Under the same testing conditions, device based on SCG ETL maintained 97% of their initial efficiency after 1440 hours. |
