本質可拉伸共軛高分子與鈣鈦礦量子點異質接面設計及其軟性光電元件應用

Abstract

隨著物聯網、光通訊、人工智慧迅速發展，人們對於高性能、低能耗軟性電子產品的需求日益增長。科學家們近期提出了低能耗新穎光感神經元元件，透過模仿人體神經突觸，整合數據處理與數據儲存於單一元件之中，並透過光通訊傳輸進一步降低元件能耗。但如何整合此類元件與軟性電子元件仍需深入研究，使這些軟性電子元件不僅擁有可拉伸和耐用的特性，同時具備高效運行、低能耗和即時數據處理等能力。為滿足這些需求，開發可拉伸性奈米複合材料是其一具前瞻性的策略，其中，結合本質可拉伸共軛高分子 (CPs)與鈣鈦礦量子點 (PeQDs)展現出巨大潛力，此奈米複合材料提供了一種簡潔的架構，並將高分子的柔韌性與PeQDs的優越光電特性結合。然而，此策略仍存在一些挑戰，包括PeQDs的自聚集、有限的電荷轉移效率及本質可拉伸高分子與PeQDs的界面問題。因此，本論文提出了多種策略，包括透過設計嵌段共聚高分子的自組裝特性、CPs的骨架設計、PeQDs的表面配體工程以及極性調控，來優化奈米複合材料並探討其帶來的元件效能影響。在第二章中，我們提出可以透過δ-癸內酯與3-己基噻吩之嵌段高分子於不同溶劑中的相分離，來改善PeQDs的自聚集問題。通過此策略可以增加3-己基噻吩晶粒尺寸的同時並改善了3-己基噻吩結晶與PeQDs之間的界面，這樣的優化，使光感神經元元件實現了最快的光響應時間（1 ms）、最高的電流對比度（4.9 × 105）、1.93的成對脈衝加成（PPF）。此外，這一方法也成功被應用於全拉伸光突觸元件，並展示其可模仿類神經肌肉突觸之特性，例如高抗拉伸性、彎曲彈性和外在脈衝刺激的可塑性。在第三章中，我們針對兩個方向進行研究，首先討論另一種本質可拉伸CPs具備柔性骨架及n型特性—萘二醯亞胺二噻吩與PeQDs的結合，以研究不同策略之本質可拉伸特性與不同傳輸類型的CPs於奈米複合材料中的影響。第二，我們通過設計不同鏈長和立體障礙的PeQDs表面配體，來進一步討論PeQDs之表面配體工程對於異質界面的影響。結果顯現雙十二烷基二甲基溴化銨提供了理想的配體適配性，增強了缺陷鈍化、改善了異質界面並降低了缺陷密度。通過對PeQDs進行表面配體工程，此複合材料實現了可在多波長光刺激及拉伸條件下，有效地模擬了光突觸特性，並展現顯著的性能指標：最快響應時間（1 ms）、最高電流對比度（3.2 × 106）、1.97的PPF、0.16 aJ的超低能耗，以及在50%拉伸應變下50 mV超低操作電壓下的類人學習行為。這些結果顯示，PeQDs的表面配體工程可實現低能耗、缺陷最小化的人工突觸。基於前兩章研究的基礎下，發現PeQDs能有效與不同傳輸特性的本質可拉伸式CPs結合，並體現卓越的光感神經元特性。因此，第四章我們提出透過錫（Sn）混摻來調控PeQDs對於電子與電動的親性，藉此影響其異質界面的載子轉換效率與捕獲傾向，並深入討論其對於不同傳輸類型的本質可拉伸p型和n型CPs之間相互作用的影響。結果顯現錫混摻方法可有效提升PeQDs之電子親和力，影響其最高佔據分子軌域。透過瞬態光電流分析，Sn摻雜的PeQDs通過增強電子捕獲提高了p型CPs的元件性能 (電流消散時間延長3倍、光電流提升1.28 × 101)，反而使n型CPs元件性能下降。因此，透過錫摻雜可選擇性調節PeQDs的捕獲特性，進一步優化p型光感神經元元件性能，像是脈衝刺激和脈衝時間的可塑性、電流和PPF數值，此外，實現了在–0.1 mV和1 ms光脈衝下的超低能耗 (0.169 aJ)，此效能優於其他p型光電突觸。透過上述實驗，本文剖析如何透過PeQDs改質與本質可拉伸CPs設計來優化改善奈米複合材料之界面，使其有效應用於新穎光感神經元元件。

The rapid development of the Internet of Things, light fidelity, and artificial intelligence has increased demand for high-performance, low-energy soft electronics. Recently, scientists have proposed advanced photosynaptic devices that mimic human synapses, integrating data processing and storage within a single device while minimizing energy consumption through optical communication. Nevertheless, additional research is required to effectively integrate these devices with soft materials, combining stretchability with efficient operation. Developing stretchable nanocomposites is a promising approach to address these demands, particularly by leveraging intrinsically stretchable conjugated polymers (CPs) with perovskite quantum dots (PeQDs). This nanocomposite provides a simple structure that merges the flexibility of polymers with the superior optoelectronic properties of PeQDs. However, challenges remain, including the self-aggregation of PeQDs, limited charge transfer efficiency, and interface issues between CPs and PeQDs. Therefore, this dissertation proposes multiple strategies, including utilizing the self-assembly of block copolymers, backbone of CPs, surface ligand engineering, and polarity of PeQDs to optimize the nanocomposite and explore its impact on device performance. In Chapter 2, we demonstrated that selecting specific solvents in poly(δ-decanolactone)-based block copolymers effectively controls the assembly of poly(3-hexylthiophene) (P3HT), leading to enhanced self-aggregation, larger grain size, and improved interfaces between P3HT and PeQDs. This approach achieved the fastest response time (1 ms), highest current contrast (4.9 × 105), and paired-pulse facilitation (PPF) of 1.93. Additionally, it enabled the creation of a fully stretchable photosynaptic device, exhibiting neuromuscular synapse characteristics such as high strain tolerance, bending resilience, and spike-dependent plasticity features. In Chapter 3, we first integrated PeQDs with another intrinsically stretchable CPs, naphthalene-diimide-bithiophene, which had a flexible backbone and n-type properties, to examine the effects of different strategies and types of intrinsically stretchable CPs. Next, by designing surface ligands for PeQDs with tailored chain lengths and steric hindrance, we optimized the interface between PeQDs and CPs. Specifically, didodecyldimethylammonium bromide provided ideal ligand accommodation, enhancing defect passivation, improving heterojunction quality, and reducing trap density. Through this surface ligand engineering, the composite effectively emulated photosynaptic characteristics under multiwavelength light stimuli and strain, achieving remarkable performance metrics: highest current contrast (3.2 × 106), PPF of 1.97, ultra-low energy consumption (0.16 aJ). These results showed that the surface ligand engineering of PeQDs facilitated the creation of low-energy, defect-minimized artificial synapses. Building on these insights, Chapter 4 focused on modulating PeQDs bipolarity through tin doping and examining its effects on interactions with p- and n- types CPs. Photocurrent analysis revealed that Sn-doped PeQDs enhanced performance with p-type CPs by boosting electron trapping, while performance with n-type CPs declined. Selective tuning of trapping characteristics improved photosynaptic responses, increasing spike-dependent plasticity and PPF ratios. Optimal Sn doping enabled ultra-low energy consumption of 0.169 aJ, surpassing other p-type photosynaptic devices. This dissertation explored how PeQDs modification and the design of intrinsically stretchable CPs can optimize the heterojunction, enhancing their practical application in novel photosynaptic devices.