介孔材料骨架於有機無機混成鈣鈦礦太陽能電池之應用

Abstract

有機無機混摻鈣鈦礦材料為新世代太陽能電池中最具潛力的材料之一，其優異的光電性質和適用低溫製程的特性，以及低成本、高效率的優勢，使其在新一代太陽能電池中異軍突起，成為最有可能商業化的有機光電材料之一，在僅僅十年之內，其最高光電轉換效率已可達到25.2%。然而因鈣鈦礦材料本身的缺陷和對水、氧及紫外光的不良穩定性，在商業化的進程中仍有重大挑戰必須克服。 在本研究中我們分別使用「金屬有機框架材料」及「共價有機框架材料」此兩種不同的介孔型材料骨架，利用其孔洞材料的特性，不僅達到介面修飾及表面鈍化的功效，更可以增加鈣鈦礦材料的穩定性，此外，除了較好的結晶性與表面型態，作為介孔型材料再加上其電子傳輸能力，更進一步提高了元件性能。除此之外，值得一提的是，比起金屬有機框架材料，共價有機框架材料擁有更高的結構可調控性，我們透過氯摻雜可以進一步調控其能階，藉由簡單摻雜可以使其作為電洞或電子傳輸層，增加了此材料使用的彈性空間。 本研究系統性的分析了介孔型材料於鈣鈦礦太陽能電池上的應用，並分別針對金屬及共價有機框架材料做不同的應用，除了增加元件性能外，更增加了鈣鈦礦材料的穩定性。

Organic-inorganic hybrid perovskite has recently attracted significant attention in fabricating low-cost and high-efficiency solar cells owing to the tremendous optoelectronic properties, including a broad and tunable light-harvesting range, decent ambipolar charge-transporting capability, and low exciton binding energy. With only a few years, the recorded efficiency of perovskite solar cells (PVSCs) has raised up to 25.2%. However, it suffers from a critical intrinsic problem of low long-term stability, such as poor ultraviolet light resistance and moisture sensitivity that dramatically damage the operational stability of PVSCs. In this thesis, we demonstrate a novel approach to enhance the associated long-term stability and efficiency of PVSCs by introducing mesoporous materials into the device, showing great potential in photovoltaic application. In chapter 2, we first employed the metal-organic frameworks (MOFs), which are three-dimensional (3D) porous crystalline materials and possess excellent moisture and chemical stabilities. The MOF/perovskite heterojunction was studied in this chapter to realize the interaction between perovskite and MOFs, and the possibility of enhancing morphology and device stability. In chapter 3, the other kinds of porous material, covalent organic frameworks (COFs) are introduced. Notably, COFs show different characteristics from MOFs, in which COFs possess better charge transfer ability owing to the 2D conjugated properties. In addition, the structure and energy level controllability of COFs enable their application diversity. For example, by simply doping COFs, the original functionality of serving as hole-transporting layer can be converted to be serving as electron-transporting layer. Such promising features of COFs present significant merits for application in PVSCs. After studying the possible applications of these porous materials in photovoltaic devices, their interactions with perovskite materials are also investigated. It is revealed that the porous feature of these materials benefits the perovskite heterojunction and enables great enhancement in performance and stability of PVSCs.