銨類與胺類添加劑對於反式鈣鈦礦太陽能電池效率及穩定性的影響及差異

Abstract

近年來，鈣鈦礦太陽能電池 (PVSCs) 因其高效率、易製備、溶液相容性佳等優勢，成為備受矚目的研究焦點之一。至今，已認證元件之光電轉換效率(PCE)達到25.7%，接近矽太陽能電池效率的水平。研究團隊使用各種方法嘗試更進一步提升PVSCs PCE，而添加劑工程正是其中一種主要的研究方法，用於鈍化鈣鈦礦晶體或表面缺陷、調節結晶過程、並優化鈣鈦礦薄膜的型態。透過適當的添加劑工程，PVSCs更進一步提升其效率及穩定性。 在第二章中，我們詳細討論了苯已胺碘化物(PEA+)和苯已胺(PEA)添加劑的差異。PEA+和PEA是兩種常見且具代表性的添加劑，然而，由於它們的結構相似，經常引起混淆且缺乏比較。因此我們透過比較銨基添加劑PEA+和胺基添加劑PEA，討論銨基及胺基添加劑對於效率及穩定性的差異。首先我們通過基本表面分析方法討論添加劑對於鈣鈦礦的作用及優勢。接著，我們在不同條件下對元件進行穩定性測試，包括低相對濕度、高相對溼度、加熱條件及光照測試。從實驗結果得知，由於PEA具有路易斯鹼特性，對於鈣鈦礦有更有效的鈍化作用。此外，PEA能夠有效防止水侵入、更好的熱穩定性及抑制碘離子遷移，進而提高元件效率及穩定性。 在第三章中，我們提出了關於實驗室未來的一些可能研究方向，包括鈣鈦礦組成工程以及自組裝單層膜的引入。鈣鈦礦組成工程在近年來經常被用於PVSCs，透過調節陽離子和陰離子的組成，實現高效率及穩定的PVSCs。自組裝單層膜則是最新研究的焦點之一，透過自組裝單層膜的引入，當作空穴傳輸層，獲得更好的鈣鈦礦層表面型態、優化層與層之間的能帶對齊、並有效的減少界面電荷再復合，進一步優化PVSCs的效率及穩定性。

Perovskite solar cells (PVSCs) have gained significant attention as promising photovoltaic devices due to their high efficiency, solution-compatible processability, ease of manufacture, and low cost [1]. At present, their certified power conversion efficiency (PCE) has reached 25.7%, approaching the value of silicon-based solar cells [2]. For PVSCs, additive engineering has become a prevailing strategy to passivate bulk or surface perovskite defects, modulate crystallization processes, and optimize the morphology of perovskite films. These improvements derive impressively high performance and stable PVSCs. In recent years, phenethylammonium iodide (PEA+) and phenethylamine (PEA) are two common and representative additives used to enhance the performance of PVSCs [3]. However, ammonium- and amine-based additives are often confused due to their structural similarities. Herein, in Chapter 2, we discuss in detail the difference between PEA+ and PEA additives, including photovoltaic performance, optical properties, electrical properties, and device stability. We first elucidate the role of additives and their benefits through several basic surface analyses such as XRD, SEM, UV, and so on. In the next part, we aged the devices under different conditions, including low relative humidity (RH40%), high relative humidity (RH70%), heated conditions at 90℃, and light illumination. The results show that PEA passivates iodide vacancies and undercoordinated Pb owing to its Lewis base characteristic. Also, PEA better prevents water invasion, enhances thermal resistance, and inhibits iodide ion migration, thus enhancing PCE and stability. As a result, PEA increases PCE by more than 15% to reach a value of > 21%. More important, the unencapsulated PEA-based device maintained 95.1% and 94.4% of their initial PCE values after storing in an N2 environment for 5000 hours and aging at RH 20% ± 5% at RT for 600 hours, respectively. In Chapter 3, we proposed some possible future works in our lab, including compositional engineering and SAM introduction. Compositional engineering is frequently researched in these years to realize high-performance and stable PVSCs by tuning the composition of cations such as MA+, FA+, and Cs+ and anions such as I-, Br-, and Cl-. By the mixed cation and anion strategy, we can fabricate PVSCs with a bandgap that approaches the theoretical Shockley-Queisser limit and stabilize the α-phase FAPbI3 perovskite. In regard to SAMs, significant improvements in surface morphology, energy band alignment, as well as reduced interfacial charge recombination can be observed after introducing SAMs as HSCs, leading to optimized PCE and stability.