有機與二維鈣鈦礦材料之光電性質及應用

Abstract

本論文涵蓋兩種材料的研究：擁有和一般有機材料不同發光機制的新穎材料－聚集誘導放光材料 (AIE material, aggregation induced emission material) 與近年來鈣鈦礦研究的新領域－二維結構與RPPs結構 (Ruddlesden-Popper perovskites, RPPs)。在AIE材料的研究中，本文選擇HPS (1,2,3,4,5-hexaphenylsilole) 作為研究對象，旨在利用其特性以溶液製程方式製作OLED (organic light-emitting diode, OLED)。在選擇材料適當的厚度後，透過「引入電洞傳輸層TFB (Poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine))」與「烘烤材料使其結晶程度提升」兩種方式優化元件量子效率，並以光學顯微鏡、螢光量子產率(Photoluminescence quantum yield, PLQY)、電性圖分析造成其效率上限之成因。與單純發光層上下接出陰陽兩極的結構相比，元件的最佳製程條件能使效率提升10倍。在二維鈣鈦礦的研究中，本文透過原創的長晶方式，實現在矽基板上快速製造大量的〖 PbI〗_2 單晶薄片。單晶薄片厚度最薄可達2奈米，並能透過溶液二步法將其轉換成單層至數層的鈣鈦礦與鈣鈦礦RPPs結構。由PL圖譜可知，薄片鈣鈦礦會因量子侷限效應的關係發生藍移，且〖 PbI〗_2 經由二步法轉換成RPPs結構後的PL特徵與長鏈陽離子包覆單層晶格 (即n=1) 的情況相符，是一種低成本製作大量低維數鈣鈦礦的方式。

This thesis covers the research works of two kinds of materials: organic molecules with aggregation-induced emission (AIE) and low-dimensional perovskites.1,2,3,4,5-hexaphenylsilole (HPS) is an organic molecule with AIE characteristics. HPS was used in this work for the fabrication of organic light-emitting diodes (OLEDs). The external quantum efficiency of the OLEDs was optimized by introducing the hole transporting material poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB) and baking the emissive layer. Optical microscopy, photoluminescence quantum yield, and IV curves were used to investigate the influence of experimental conditions on device performance. We found that the device performance can be improved for ten times after adding TFB as the hole transporting layer.Low-dimensional perovskite flakes were realized by preparing PbI_2 flakes on 〖Si/SiO〗_2 substrates and converting PbI_2 flakes to perovskite flakes via two-step method. The PbI_2 thickness of 2 nm was achieved. The blue-shift of the wavelength of the photoluminescence peak was observed when decreasing the thickness of the flakes, which was attributed to the quantum confinement effect. Besides, if phenethylammonium (PEA) was used for conversion, Ruddlesden-Popper perovskite with n = 1 was realized.