激發態質子轉移的光譜和動力學研究：機械力誘導發光、放大自發發射和窄帶發射OLED應用

Abstract

本論文針對激發態分子內質子轉移（ESIPT）反應及其光物理行為進行探討，研究對象涵蓋三類具代表性的分子系統：具氫鍵結構的茚酮衍生物、3-羥基黃酮互變異構體，以及具有雙氫鍵結構的紅光OLED發光材料。每個系統分別展現ESIPT在機械誘導、互變異構與固態發光效率等方面的獨特性。

第一章中，我們研究一系列具備RR'N–H···O=C類型分子內氫鍵的茚酮衍生物，透過改變R'基團的電子接受能力，有效調控氫鍵強度與ESIPT效率。其中，化合物4（R' = COCF₃）展現出新穎的機械力誘導型ESIPT現象，即在固態晶體中僅藉由機械應力促使ESIPT產生。提供一種新的ESIPT調控途徑。

第二章探討一種3-羥基黃酮衍生物PRA-3HC，該分子在溶液中以兩種互變異構體共存，分別具有雙氫鍵（N1-H）與單氫鍵（N2-H）結構。此系統可用於研究基態異構化、溶劑依賴的激發態質子轉移（ESIPT）行為，以及氫鍵在光穩定性中的角色。在特定激發條件下觀察到的放大自發輻射（ASE）現象，提供了一個敏感的手段來探測激發態動力學與分子構型分布。透過與單甲基取代物（N1-Me與N2-Me）的比較研究，進一步揭示了氫鍵排列對穩定性與光物理性質的影響。

第三章中，我們開發出一系列雙氫鍵型ESIPT發光分子DPNA、DPNA-F與DPNA-tBu，這些分子產生快速且高效率的ESIPT，並獨特地以KK態單一型式發光。其發光波長超過650奈米，呈現深紅色窄頻光譜，並具備高光致發光量子產率（PLQY）。基於此材料，我們製作出紅光有機發光二極體（OLED），在外部量子效率（EQE）、色純度與穩定性方面均達到優異表現，成功滿足BT.2020色域標準對紅光顯示的要求。

總結而言，本論文展現了透過分子內氫鍵設計與調控，能有效掌握並調變ESIPT系統之光物理性質，為未來ESIPT材料在高效顯示器、光電元件與感測技術中的應用提供了堅實的理論基礎與實驗指引。

This thesis investigates excited-state intramolecular proton transfer (ESIPT) phenomena and their photophysical properties through three distinct classes of compounds: hydrogen-bonded indanone derivatives, 3-hydroxyflavone-based tautomers, and red-emitting OLED materials with dual hydrogen bonds. Each system highlights different aspects of ESIPT, including mechanically induced activation, tautomer-dependent photostability, and efficient solid-state emission.

In Chapter 1, a series of indanone derivatives bearing RR’N-H…O=C-type intramolecular hydrogen bonds was developed. By introducing different electron-withdrawing groups (R’), we successfully modulated the strength of the hydrogen bond and the ESIPT efficiency. And compound 4 (R’ = COCF₃) demonstrated a remarkable and previously unobserved phenomenon: mechanically induced ESIPT in the crystalline state. This behavior was attributed to its non-centrosymmetric crystal packing and strong intramolecular hydrogen bonding, highlighting a new strategy for activating ESIPT via external mechanical force.

Chapter 2 examines a 3-hydroxyflavone analogue, PRA-3HC, which exists as a dynamic equilibrium between two tautomers: one featuring dual intramolecular (N1–H) hydrogen bonds, and the other containing a single (N2–H) hydrogen bond. This system allows investigation into ground-state isomerization, solvent-dependent ESIPT behavior, and the role of hydrogen bonding in photostability. The occurrence of amplified spontaneous emission (ASE) under certain excitation conditions provides a sensitive probe of the excited-state dynamics and structural population. Comparative studies using monomethylated analogues (N1-Me and N2-Me) further reveal how specific hydrogen-bonding patterns influence both stability and photophysical properties.

Chapter 3 presents a newly developed family of ESIPT-active emitters, DPNA, DPNA-F, and DPNA-tBu designed to support dual intramolecular hydrogen bonds and facilitate highly efficient ESIPT in the solid state. These materials exhibit fast ESIPT kinetics and generate narrowband deep-red emission exclusively from the KK tautomeric form, with emission maxima beyond 650 nm. The compounds also display high photoluminescence quantum yields, making them ideal candidates for use in organic light-emitting diodes (OLEDs). Devices based on these emitters show high external quantum efficiency (EQE), minimal efficiency roll-off, and emission profiles that meet the BT.2020 color standard for red-light emission.

Overall, this work demonstrates how rational molecular design focused on hydrogen-bond engineering can be used to precisely control ESIPT behavior, photostability, and emission properties. These findings provide valuable insight into the structure–property relationships in ESIPT systems and pave the way for future developments in organic photonics and optoelectronics.