氧化亞銅薄膜之高功率脈衝磁控濺鍍製程開發及其在鈣鈦礦太陽能電池之應用

Abstract

太陽能是一種可再生能源，可以利用潔淨的能源技術將其轉換為電能。本研究第一部分運用直流磁控濺鍍(DCMS)以不同氧流率比(fO2)濺鍍p型CuxO薄膜作為鈣鈦礦太陽能電池的電洞傳輸層。研究發現在fO2=17.5%時可獲得較佳之能量轉換效率7.90%。接著我們改變不同Cu2O薄膜之厚度，發現膜層越薄效率越高，在膜厚5 nm時其能量轉換效率可升高至9.37%。隨後採用高功率脈衝磁控濺鍍(HiPIMS)系統鍍製p型Cu2O薄膜，元件之效率可達10.29%。因為HiPIMS具有高離化率的特點，鍍膜之薄膜更緻密且具有低表面粗糙度，此有助於減少薄膜內或界面的缺陷，使漏電流下降。進一步運用HiPIMS搭配中頻電源之疊加型高功率脈衝磁控濺鍍(疊加型HiPIMS)系統製備p型Cu2O薄膜以應用於鈣鈦礦太陽能電池之電洞傳輸層(HTL)，其能量轉換效率可進一步提升至15.20%，短路電流密度(Jsc)、開路電壓(Voc)和填充因子(FF)值分別為20.57 mA/cm2、0.977 V和76.5%，此能量轉換效率為近年在全世界採用各種不同製程之單層Cu2O薄膜應用於鈣鈦礦太陽能電池的電洞傳輸層之所有團隊中居於領先地位。 接著第二部分我們更進一步採用疊加型HiPIMS p型Cu2O薄膜並塗佈sol-gel NiO薄膜以形成雙層(疊加型HiPIMS Cu2O+濕式NiO)電洞傳輸層，研究發現元件能量轉換效率可再提升至20.15%，其Jsc、Voc和 FF值也分別再升高為23.26 mA/cm2、1.096V和79.0%。最後將元件放置於手套箱內測試其保存1000小時以上之元件穩定性，結果發現疊加型HiPIMS Cu2O單層電洞傳輸層元件仍可維持98%的初始效率，而雙層(疊加型HiPIMS Cu2O+濕式NiO)電洞傳輸層更可維持99.4%的初始效率。相較於文獻採用有機高分子電洞傳輸層在相同的測試環境及時間下元件效率僅剩下70~90%之間，顯然本研究採用無機p型氧化物薄膜作為鈣鈦礦太陽能電池電洞傳輸層不僅可獲得高能量轉換效率，同時也具有優異的界面穩定性及耐久性。

Solar light is a renewable source of energy that can be used and transformed into electricity using clean energy technology. In this study uses direct current magnetron sputtering (DCMS) to sputter p-type CuxO films with different fO2 as the hole transport layer for perovskite solar cells. The study shows better PCE of 7.90% when fO2=17.5%. By changing the thickness of Cu2O thin films, the higher PCE can be further increased to 9.37% when the thickness is 10 nm. Subsequently, a high-power impulse magnetron sputtering (HiPIMS) p-type Cu2O film offers improved device efficiency of 10.29%. As HiPIMS has the characteristics of a high ionization rate, it can make the film denser with low surface roughness, which reduces the defects of the film and interface and also reduces leakage current. In addition, use the superimposed high power pulse magnetron sputtering (superimposed HiPIMS) system to deposit p-type Cu2O films for application as the hole transport layer of perovskite solar cells. With this method, the PCE improved by 15.20%, Jsc, Voc, and FF are 20.57 mA/cm2, 0.977 V and 76.5%, respectively. This efficiency is in the leading position among all teams in the world in recent years using single-layer Cu2O film as the hole transport layer of perovskite solar cells. In the second part, superimposed HiPIMS p-type Cu2O films were coated with sol-gel NiO films to form a double-layer hole transport layer. The device accomplishes significant efficiency as high as 20.15%, and the Jsc, Voc, and FF further increased to 23.26 mA/cm2, 1.096 V, and 79.0%. Finally, we kept the devices in a glove box for more than 1000 hours to test their stability. The superimposed HiPIMS single-layer Cu2O can remain at 98% of the initial efficiency, and the double-layer (superimposed HiPIMS Cu2O+sol-gel NiO) can even maintain 99.4%. Compared with the literature using organic polymer hole transport layer, only about 70-90% remains at the same aging time. In this study, inorganic p-type oxide film as a hole transport layer in perovskite solar cells not only achieves high PCE but also has excellent interface stability and durability.