醣類雙嵌段高分子材料於光電記憶體之應用

Abstract

有機高分子電子元件的迅速發展，使柔性、功能性且環境友善的材料得以成為次世代資訊儲存裝置的核心。有機光致電晶體記憶體因具備多刺激響應特性、非侵入式讀取方式，以及低能耗光操作而備受關注。為解決如今所面臨的環境議題與性能限制，本論文聚焦於生質高分子組裝與混成奈米複合材料的合成研究，藉由設計結構結合光電晶體功能性與材料柔韌性，以應用於光致電晶體記憶體之開發。 第二章中，設計低聚合度高度不相容(low-N high-χ)之麥芽七醣(Maltoheptaose)為基礎的嵌段共聚物（Block copolymers, BCPs），以親水端分散鈣鈦礦晶體，藉由嵌段共聚物自組裝控制奈米尺度區域，限制並分散鈣鈦礦奈米晶體成長，以非連續記憶缺陷儲存分離後的載子形成浮閘記憶體(floating-gate memory)，顯著影響提升電荷分離效率、擴展光致記憶視窗以達到高效能光致電晶體記憶體。 在第三章，進一步發展具有不同分支結構（AB、AB2、AB3）的麥芽三醣(Maltotriose)嵌段共聚物，以探討醣類分子分支對鈣鈦礦量子點分散與自組裝行為的影響。結果顯示，分支架構能強化相分離並改善量子點分散均勻性，配合優化介面能階，以電荷儲存穩定性。其中，AB₃ 結構展現超過 106 的開關電流比與優異的操作穩定性，歸因於其自組裝球狀結構與精準的能階調控。 第四章，將醣基嵌段高分子進一步自組裝限制有機光響應小分子形成奈米複合材料薄膜，目前初步探討混入吡烯羧酸（pyrenecarboxylic acid）後的形貌與光學變化影響光致電晶體；未來工作預期藉由溶劑交換法製備出具核心–殼層結構的混成，藉此醣基嵌段高分子自組裝外殼包覆光響應吸光物質為中心，以分散光響應小分子於高分子基質中。 本論文完整描繪了高分子光致電晶體記憶體中「永續性」、「分散性」與「功能性」三者的融合藍圖。所開發的生質區塊共聚物與混成材料不僅揭示奈米尺度形貌對電荷儲存機制的影響，更為未來環境友善型光電與記憶元件材料提供重要設計範例。

The rapid pace of organic and polymeric electronic devices has enabled the realization of flexible, multifunctional, and environmentally friendly materials specific for next-generation information storage devices. As part of this effort, organic phototransistor memories have received much attention due to their multi-stimulus responsiveness, non-invasive readout, and prospect for low-energy optical programming. For addressing the environmental problems and performance penalties involved with devices, this dissertation focuses on the synthesis of bio-derived polymer assemblies and hybrid nanocomposites joining structural flexibility with phototransistor functionality for phototransistor memory applications. Chapter 2 introduces low degree of polymerization and high incompatibility (low-N high-χ) carbohydrate-based block copolymers (BCPs). The hydrophilic oligosaccharide moieties are used to distribute the perovskite nanocrystals, whereas the self-assembly of the BCPs allows for dimensionally controllable domain regulation, thus spatially distributing the perovskite nanocrystal growth to accommodate separated charge carriers. This structural design optimizes charge separation efficacy and widens the photo-induced memory window to achieve phototransistor memory with high performance. Carbohydrate-based BCP with different branched architectures (AB, AB2, and AB3) in Chapter 3 were also designed to investigate the impact of carbohydrate branching on the dispersion and self-assembly performance of perovskite quantum dots (QD). The results indicated that the branched architectures reinforced the microphase separation and dispersed the QD distribution, and the optimized interfacial energy-level alignments with a view toward enhancing the stability of the charge storage. The branched architectures promoted stronger phase segregation and more uniform QD dispersion compared to the other counterparts, leading to more stable charge storage and more effective confinement. The optimized AB₃ configuration demonstrated an enhanced ON/OFF ratio exceeding 10^6, along with enhanced operational stability, attributed to its energy levels alignments and self-assembled sphere nanostructure. Chapter 4 describes the carbohydrate block copolymers self-assembled in an effort to confine organic photo-responsive small molecules in nanocomposite thin films. So far, blending the light-harvesting pyrenecarboxylic acid controlled the morphology and optical property, influencing on the phototransistor memory. The subsequent effort is to develop core–shell hybrid nanostructures by the solvent-exchange route with the self-assembled carbohydrate shell of the block copolymer surrounding photoactive light-harvesting molecules serving as the core aiming to create photo-responsive constituents well dispersed within the polymeric matrix. This dissertation provides a complete blueprint for the convergence of sustainability, structural performance, and functional performance for polymeric phototransistor memories. The biobased block copolymeric materials and hybrid materials not only outline charge-storage principles based on nanoscale morphology, but also lay out a template for environmentally friendly materials for future optoelectronic and memory devices.