銫機無機鈣鈦礦擁有良好的環境穩定性，已被廣泛運用到光電元件上，而有必要了解鈣鈦礦的載子複合機制。無機鈣鈦礦具有較大的激子束縛能，因此光激發載子的複合在室溫下由激子主導。當晶體中存在缺陷態時，自由激子會被束縛住形成侷域激子，進而限制了載子的移動。在許多報導中皆觀察到了侷域態存在於鈣鈦礦中。然而，目前還沒有研究明確指出鈣鈦礦中的載子侷域效應主導機制為何。因此，釐清鈣鈦礦中的侷域態形成主因將有助於提供改善光電元件的策略。
在本論文中我們以化學氣相沉積法製備溴化銫鉛(CsPbBr3)鈣鈦礦微米晶體。我們選擇了簡單的氧處理對溴化銫鉛鈣鈦礦進行缺陷鈍化，以確保晶體含有較低的缺陷態。透過材料分析，我們發現原始溴化銫鉛鈣鈦礦微米晶體為雙相溴化銫鉛鈣鈦礦參雜了准二維衍生相(CsPb2Br5)，經過氧處理後的晶體則為單相溴化銫鉛鈣鈦礦晶體。首先我們先釐清兩種晶體的載子複合機制。從激發功率相關的光致發光光譜，我們觀察到雙相溴化銫鉛中含有陷阱態，而兩種晶體的載子複合都由激子主導。經由變溫光致發光螢光光譜，確定雙相鈣鈦礦中的發光機制由侷域激子主導，而單相鈣鈦礦中則存在多種激子機制。最後，為了進一步釐清侷域激子的形成原因，我們執行時間解析光致發光(TRPL)測量以及分析不同發光能量的載子生命期。證實了雙相溴化銫鉛有更深的陷阱態。結合多激子態結構與載子弛豫行為，我們可以確定在溴化銫鉛中的載子侷域行為是由偏極子主導。此外，我們也證實了氧氣可以有效鈍化鈣鈦礦的深層缺陷。

Cesium‐based inorganic perovskites have been widely used in optoelectronic devices because of their stability. It is necessary to understand the mechanism of the carrier recombination. Due to the large exciton binding energy of inorganic perovskites, the exciton dominates the charge carrier recombination at room temperature. Free excitons will be bound in localized states to form localized excitons. It has been observed that localized states exist in perovskites. However, the origin of these localized states has not been fully understood. Therefore, clarifying the leading cause of carrier localization in perovskites will help provide strategies for improving optoelectronic devices.
In this work, we synthesized perovskite microcrystals by the chemical vapor deposition (CVD) method. We chose oxygen treatment to passivate defects to ensure that the crystal contains low defect states. Through material analysis, we found that the original perovskite microcrystal is a dual-phase CsPbBr3-CsPb2Br5 perovskite, and we obtained single-phase CsPbBr3 microcrystals via oxygen treatment. Through performing power-dependent PL and temperature-dependent PL, We clarified that the mechanism of light-emission is dominated by localized exciton in dual-phase CsPbBr3-CsPb2Br5. In contrast, the multi-exciton states exist in single-phase CsPbBr3. To further understand the origin of the carrier localization, we carried out the time-resolved PL(TRPL) and energy-dependent TRPL measurements. We confirmed that the deep trap exists in dual-phase CsPbBr3-CsPb2Br5. Combining the multi-excitonic state structure and carrier relaxation behavior, we can determine that carrier localization is dominated by the polarons in perovskites. In addition, we have also confirmed that oxygen can effectively passivate the deep defects of perovskite.

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