烷基單胺和雙胺鈍化層對鈣鈦礦太陽能電池元件特性的影響

Abstract

鈣鈦礦太陽能電池因高轉換效率和製造友善性而被視為有前景的光伏元件材料，但由於鈣鈦礦材料製造過程容易形成缺陷，使得其發展仍受到阻礙。使用胺基化合物進行界面鈍化修飾已被證明減少鈣鈦礦材料缺陷形成的有效方法。本研究針對單胺類的己基溴化銨（C6Br）和雙胺類的己烷-1,6-二胺鹵化銨（HDABr），這兩種己基銨鹵化物進行測試，將其作為修飾倒置式鈣鈦礦太陽能電池元件的界面材料。將這兩種材料進行三種界面修飾，分別是在載子傳輸層(HTL)與鈣鈦礦吸光層(PVSK)界面、PVSK與電子傳輸層（ETL）界面、同時在這兩個界面上進行修飾。在修飾材料的性質上，己基銨鹵化物因為具有較大的烷基官能基，能夠增加PVSK層的親水性，同時胺基與鈣鈦礦相互作用下，抑制了缺陷的形成。因此，無論是C6Br還是HDABr，作為HTL/PVSK或PVSK/ETL界面修飾層，都能明顯提高鈣鈦礦太陽能電池元件性能，其中又因為HDABr擁有雙胺，在界面上提供了更多缺陷修飾的機會，進而能展現出較佳的效果。值得一提的是，同時在HTL/PVSK和PVSK/ETL界面上應用C6Br或HDABr鈍化修飾並未呈現附加效應。在雙界面鈍化下，C6Br會導致元件效率下降，而HDABr鈍化後的元件效率提升則比單一界面鈍化修飾後要小。這種結果可以被歸因於己基銨鹵化物的電絕緣性質，當同時應用於HTL/PVSK和PVSK/ETL界面時，會導致載子傳輸過多的障礙。最後，我們的研究為鈣鈦礦太陽能電池元件使用胺基化合物鈍化修飾材料在選擇和設計上提供了有用的見解。

Perovskite solar cells (PSCs) are a promising type of photovoltaic devices thanks to their high-power conversion efficiency (PCE) and manufacturing-friendliness, but their development is still hindered by the strong defect-forming tendency of the perovskite (PVSK) light-absorbing materials. Interfacial passivation using amine-based compounds has been demonstrated to be an effective method for suppressing defect formation in PSCs. This study examined two types of hexylammonium halides—n-hexylammonium bromide (C6Br), which is monofunctional, and hexane-1,6-diammonium bromide (HDABr), which is bifunctional—as passivation materials for various interfaces of an inverted PSC device, including at either one of the hole-transporting layer (HTL)/PVSK and the PVSK/electron-transporting layer (ETL) interfaces, and simultaneously at both of those interfaces. The selected hexylammonium halides increased the PVSK layer’s hydrophobicity upon their application as passivation layers thanks to their large alkyl moiety, while their ammonium functional groups interacted with PVSK to suppress defect formation. As a result, both C6Br and HDABr yielded distinct enhancements in PSC device performance as either an HTL/PVSK or a PVSK/ETL interface-passivation layer, with HDABr showing superior effects owing to its bifunctionality providing more passivating opportunities for defects at the interface. Applying C6Br or HDABr at both of the HTL/PVSK and PVSK/ETL interfaces intriguingly did not exhibit additive effects, with C6Br causing slight degradation of device PCE while HDABr producing smaller PCE improvements than in the cases of single-interface passivation. This lack of additive benefits was attributed to the electrically insulating nature of the hexylammonium halides, which when applied at both of the HTL/PVSK and PVSK/ETL interfaces caused excessive barriers to carrier transport. Our work provided useful insights for the selection and design of amine-based passivating materials for PSCs.