本研究以二步法製備鈣鈦礦薄膜，在第二步浸泡CsBr中，以不同浸泡次數志製備出的薄膜應用於光感測器上，利用鈣鈦礦本徵半導體，以及搭配P型與N型材料會形成P-I-N結構的特性達元件效率優化。由於是利用P-I-N製作的鈣鈦礦光感測器，通常比普通的二極體擁有更寬的空乏層，更大的接面電阻和更小的接面電容，致使有著自供電的性能以及良好的效率；此外，CuSCN作為P-I-N型的鈣鈦礦光感測器P型材料研究較少，穩定性佳，且其能隙位於3.6-3.9eV能使紫外光有效吸收。本研究以UV-vis、XRD、SEM、AFM及UPS來探討鈣鈦礦與CuSCN的材料機制，採取以不同浸泡次數製備鈣鈦礦薄膜，發現隨著浸泡次數的增加，在1~4次浸泡次數下，薄膜都有位於15.30°、21.73°、30.64°和37.76°的峰, 分別對應CsPbBr3鈣鈦礦的(100)、(110)、(200)和(211)晶面(PDF#54-0752). 浸泡次數較少時，薄膜的11.83°的特徵峰更為明顯，對應CsPb2Br5的(002)晶面(PDF#25-0211)。在溶液法製備CsPbBr3的過程中，CsPb2Br5總是存在，隨著浸泡CsBr的次數不斷增加，CsPb2Br5逐漸向CsPbBr3轉化，XRD結果中CsPbBr3位於15.30°、 21.73°、30.64°的特徵峰增強，在4次浸泡後Cs4PbBr6在13.05°的相出現。能帶的部分，在浸泡3次時鈣鈦礦I層的能帶最能符合P層的CuSCN與N層的ZnO，並擁有最高的吸收峰。在SEM表面的部分，隨著浸泡的次數增加，鈣鈦礦的晶粒越來越大，且排列緊密，在浸泡4次後，過度的反應及退火開始讓晶界消融。
在CuSCN的部分，目前常用於旋塗的CuSCN溶劑是二乙硫醚(DES)，DES是一種極溶劑，會對鈣鈦礦薄膜造成侵蝕，本實驗採用了幾種不同的去除DES的方式並對其做AFM與接觸角的分析，可以發現使用低壓(LPT)處理的薄膜，因為能更快更有效的除去DES，降低DES對鈣鈦礦層的侵蝕，所以得到的粗糙度較低，而接觸角的部分，不管是用何種方式處理的CuSCN薄膜，都有著大的接觸角(>90o)，代表CuSCN是一個很好的疏水性材料，可以幫助容易水解的鈣鈦礦元件提升效率。
於元件端本研究目的是藉由改變鈣鈦礦薄膜的浸泡次數，以及不同的去除DES方式製備CuSCN薄膜來提升元件效率，元件的響應時間皆小於1秒，在響應度部分，可由原本10mA/W提升至13mA/W提升了1.3倍，有效提升元件表現。經過LPT處理後的CuSCN，因為更有效且快速的除去了DES，降低其對鈣鈦礦薄膜的侵蝕，在暗電流上有著顯著的降低，最低可達到1.28x10-12(A)，極低的暗電流使得開關比也提升到了4.2×106，極高的開關比可以有效提升元件在應用上的潛力。

In this study, we optimized perovskite and CuSCN films using different soaking times and ways of removing DES, respectively. When we changed the soaking times, we found that the crystal phase of the perovskite gradually changed from CsPb2Br5 to CsPbBr3 when we increased the soaking times. In order to meet the requirements of high-performance photosensors in polycrystalline films, larger crystal grains need to be formed and the crystal phase needs to be more consistent. Poor crystallinity and too much CsPb2Br5 will lead to smaller crystal grains. Then, we discuss the effect of different DES removal methods on the properties of CuSCN thin films. The LPT treatment method has a higher photocurrent than the annealing, and the 60-minute treatment has a higher photocurrent than the 30-minute treatment. The reason is that the LPT can remove the DES more effectively than the annealing and reduce its erosion to the perovskite, and the treatment is longer. time to remove DES more completely. In this study, we found that the device had the highest responsivity when the number of immersion was 3 and CuSCN was treated with LPT for 60 min. This is because the reaction of perovskite is more complete, with larger grains and consistent crystallographic orientation, and LPT can better remove DES and reduce the erosion of perovskite.
Keywords : perovskite film, cuprous thiocyanate film, zinc oxide nanopillars, XRD, self-powered UV light sensor element

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