有機長效及室溫磷光材料開發與浮閘式光電晶體元件應用

Abstract

本研究以有機場效電晶體為基礎，探討純有機長效室溫磷光與有機長延遲發光材料於浮閘式光記憶體與突觸元件中的應用潛力。有機場效電晶體具有結構可調性、可溶液製程與柔性基板相容等優勢，為新世代非揮發性光控記憶元件的理想平台。然而，傳統記憶材料多受限於瞬時激發與快速復合機制，難以達到長時間記憶保持與低功耗光寫入功能，因此本研究嘗試導入具延遲激發態特性的發光材料，以突破現有技術瓶頸。 於第二章中，我們選用兩種無添加金屬之室溫磷光分子，3,3',4,4'-二苯基磺醯四羧酸二酐與 3,3′,4,4′-苯酮四甲酸二酐，分別與聚苯乙烯共混製成浮閘介電層，並搭配p型半導體五苯製備成三端浮閘式光記憶元件。此結構展現良好的光輔助寫入行為，在265奈米紫外光與正閘極電壓條件下可有效儲存電子，並展現高達106的開關電流比與超過10,000秒之穩定性。此外，此元件同時具備優異的光突觸可塑性，包括成對脈衝促進、脈衝數目依賴性可塑性、脈衝時序依賴性可塑性、脈衝頻率依賴性可塑性與脈衝強度依賴性可塑性等突觸行為，進一步模擬類神經網路辨識手寫數字，顯示其於人工感知與學習系統中之應用潛力。 於第三章中，我們進一步探討以聚甲基丙烯酸甲酯為主體基質、並摻入四苯基聯苯胺、雙(1-萘基)-雙(苯基)聯苯胺或2,7-雙(1-萘基苯胺)-9,9-二甲基芴作為客體之有機長延遲發光系統。藉由調控客體濃度與能階設計，達成可見長效餘暉與顯著的電荷儲存效應。結果顯示，5 重量百分比的2,7-雙(1-萘基苯胺)-9,9-二甲基芴元件展現最佳表現，開關電流比高達4.9 × 105，並具備10,000秒以上之穩定性。然而，其載子狀態高度穩定亦造成抹除效率下降，顯示有機長延遲發光機制在提供長效儲存優勢的同時，也需解決其電性可逆性之挑戰。 綜合而言，本研究首次系統性驗證純有機長效室溫磷光與有機長延遲發光材料於有機場效電晶體光記憶元件中的應用潛力，成功結合激子工程與元件架構，實現高效率、可光寫入且具環境穩定性之非揮發性記憶系統。此結果為未來開發有機記憶技術提供具體的材料選擇與設計策略。

This thesis explores the integration of purely organic room-temperature phosphorescent (RTP) and organic long-persistent luminescent (OLPL) materials into organic field-effect transistor (OFET) platforms for high-performance floating-gate photomemory and synaptic devices. Owing to their structural tunability, solution-processability, and compatibility with flexible substrates, OFETs have emerged as promising candidates for non-volatile memory technologies. However, conventional OFET memory architectures often face limitations in data retention and optical programming efficiency due to the rapid recombination dynamics of typical charge storage materials. To address this, we introduce metal-free organic luminophores with long-lived excited states to enable energy-efficient and optically controllable memory operations. In Chapter 2, we employ two metal-free RTP molecules, 3,3′, 4,4′-Diphenyl sulfone tetracarboxylic dianhydride and 3,3′, 4,4′-Benzophenone tetracarboxylic dianhydride, which are blended with polystyrene to form the floating-gate dielectric layer. Integrated with the p-type semiconductor pentacene, the resulting OFET memory devices demonstrated robust photo-assisted electrical writing under 265 nm UV light, achieving a high ION/IOFF of ~106 and stable data retention exceeding 10,000 seconds. These RTP-based devices also exhibited excellent synaptic plasticity, including paired-pulse facilitation, pike-number-dependent plasticity, spike-timing-dependent plasticity, spike-rate-dependent plasticity, and spike-intensity-dependent plasticity, and were further validated in a neural network simulation for handwritten digit recognition, highlighting their potential for neuromorphic applications. Chapter 3 extends the study to OLPL-based systems using poly(methyl methacrylate) as the host matrix and N,N, N′,N′-Tetraphenylbenzidine, N, N′-Bis(naphthalen-1-yl)-N, N'-bis(phenyl)-benzidine, or 2,7-Bis(N-(1-naphthyl)aniline)-9,9-dimethylfluorene (DMFL-NPB) as guest molecules. By optimizing energy level design and guest concentration, we achieved visible persistent luminescence and stable charge trapping behavior. Among all systems, the device incorporating 5 wt% DMFL-NPB showed the most pronounced performance, an ION/IOFF ratio of 4.9 × 105, and excellent retention over 10,000 seconds. However, due to the strong stabilization of trapped charges, the erase operation remained incomplete, revealing a trade-off between long-term retention and rewritability. In summary, this work presents a systematic demonstration of RTP and OLPL materials in OFET-based memory architectures, offering new strategies for exciton engineering and optoelectronic device design. These findings establish a pathway toward the development of purely organic, light-controllable, and flexible memory technologies.