近年來隨著類神經網路系統的崛起，有許多研究團隊將鹵化物鈣鈦礦材料製成元件，應用於人工突觸的操作，並成功地透過外在刺激如電脈衝或光脈衝來調控元件受到刺激後所產生的電流大小，以此來模擬生物突觸權重上的變化，並且將其整合於類神經運算系統中來運作，期許實現能夠同步運算及記憶的高效能網路。
在鹵化物鈣鈦礦元件中，可以透過對元件施加電場，使鈣鈦礦中的鹵素陰離子從原本的位置脫離遷移至電極與鈣鈦礦的交界處，形成鹵素陰離子空缺，並再受到電場的驅動而遷移形成局部導電路徑，使器件的電阻降低，進入低電阻狀態。而施加反向電場時，陰離子空缺的遷移方向相反，導致先前形成的導電路徑被破壞轉變回高電阻狀態。而此特性使得鹵化物鈣鈦礦材料可以被使用於人工突觸的元件，來模仿生物突觸之行為。
而因一般常用的鹵化鉛鈣鈦礦中的鉛金屬中的毒性對生物及環境都會造成影響，因此在本研究中使用對環境較友善且擁有良好的環境穩定性之無機銫鉍鹵化物鈣鈦礦Cs3Bi2I9-xBrx作為人工突觸元件之主動層，並透過改變其鹵素離子I -與Br -之比例，來觀察其薄膜以及做成元件時的表現。首先，在 4.1節透過對薄膜進行其吸收圖譜、拍攝SEM以及XRD的量測，可以發現當x逐漸增加後材料會逐漸從Cs3Bi2I9之P63/mmc結構，逐漸轉變為Cs3Bi2Br9之P m結構，且在Cs3Bi2I7Br2(x = 2)時會同時出現以及兩種結構的特徵，而在Cs3Bi2I6Br3(x = 3)時會有最佳的薄膜結晶性。
接著在 4.2節將其製作成元件進行電性的量測，首先透過給予元件正/負電壓的掃幅來得到其電壓電流特性曲線，並以此來觀察各元件之電阻轉換行為，可以發現在Cs3Bi2I6Br3(x = 3)薄膜之元件有最低的暗電流值及最大的電流開關比，呼應到對薄膜的分析可以驗證當薄膜中缺陷較少的時候可以降低其暗電流的值，因為材料中的缺陷會降低電子躍遷至導帶的能障，使得元件阻值變小，暗電流提高。再來透過給予元件不同條件的電脈衝刺激，模擬各種突觸可塑性行為，如成對脈衝促進行為(paired pulse promotion，PPF)、脈衝次數依賴可塑性(spike-number-dependent plasticity，SNDP)、脈衝頻率依賴可塑性(spike-frequency-dependent plasticity，SFDP)及脈衝持續時間依賴可塑性(spike-duration-dependent plasticity，SDDP)。並發現在各項量測中Cs3Bi2I6Br3(x = 3)薄膜之元件相較於其他元件皆擁有最佳的電流增益情形，表示其具有最佳的人工突觸特性，其原因為Cs3Bi2I6Br3(x = 3)薄膜擁有最佳的結晶性以及存在最少的缺陷，使得此元件在脈衝讀取偏壓下擁有最低的讀取電流，並且也因此使得鹵素陰離子與鹵素陰離子空缺在遷移時需要克服的遷移勢壘更大，因此在給予電脈衝刺激形成陰離子空缺導電通道後，比起其他元件會需要更長的時間進行離子遷移使元件回到原本的高阻態狀態，因此使Cs3Bi2I6Br3(x = 3)的元件可以擁有更高的電流增益變化量。

In recent years, with the rise of artificial neural network systems, numerous research teams have developed devices using halide perovskite materials for applications in artificial synapses. These devices can successfully regulate the magnitude of the generated electrical current through external stimuli such as electrical or optical pulses. This approach mimics the synaptic weight changes observed in biological synapses and integrates these components into neural computing systems, aiming to achieve highly efficient networks capable of synchronous computation and memory.
Lead halide perovskite materials have been widely applied in artificial synaptic devices with numerous successful applications. However, the toxicity of lead metal poses significant limitations on the future development of devices based on this material, as it can have adverse effects on the environment. To address the toxicity of lead halide perovskites commonly used, in this study we use environmentally friendly and stable inorganic cesium bismuth halide perovskite, Cs3Bi2I9-xBrx, as the active layer for artificial synaptic device. By altering the ratio of halide ions I- and Br-, the performance of the thin films and the fabricated devices was investigated.
After conducting various measurements, it was observed that Cs3Bi2I6Br3 (x = 3) demonstrated superior performance with improved crystallinity, reduced dark current, and the best synaptic plasticity behaviors, making it a promising candidate for efficient artificial synaptic applications.

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