光電高分子材料與元件之特性研究

ELECTRO-OPTICAL PROPERTIES OF POLYMERIC MATERIAL BASED DEVICES

本文針對電激發光高分子、強誘電性液晶高分子與二次非線性光學高分子之材料與元件特性進行研究，內容包含高分子材料之化學結構設計合成、光電元件製作及光電特性探討。高分子電激發光元件之亮度與效率受到元件之正電極處理方式、高分子發光薄膜厚度及負電極種類所影響。以氧氣電漿作正電極表面處理、發光薄膜厚度為80 nm、金屬鈣及鋁為負電極膜層之高分子發光元件，具有較高之亮度與效率。強誘電性側鏈液晶高分子之液晶相行為、自發偶極值、驅動應答速度與液晶基之化學結構、末端旋光基團種類、側鏈液晶基含量有關。經由化學結構之最佳化設計，已獲得具有寬廣旋光層列C相及優越光電性質之強誘電性側鏈液晶高分子。對於一由矽氧烷偶氮染料與有機可溶性聚亞醯胺所製備之二次非線性光學高分子材料，其二次非線性光學係數及其熱穩定性則與發色團基之含量和高分子材料之交鏈結構相關。非線性光學係數隨著偶氮染料含量增加而提升，並以網狀互穿交鏈型高分子材料具有較佳之熱定性。有機／無機混成高分子及半網狀互穿交鏈型高分子相對上具有較差之非線性光學熱穩定性。一系列光電高分子材料之化學結構、元件結構及其光電特性之相關性已在本文中詳細探討。

The relationship among the chemical structure, device configuration, and electro-optical properties was studied for opto-electronic polymeric materials, including light emitting polymers (LEP), ferroelectric side chain liquid crystalline polymers (FLCP), and second-order nonlinear optical (NLO) polymers. For a light emitting device (LED), the brightness and efficiency are affected by the anode surface, the film thickness of the LEP, and the metal component of the cathode of the polymer light emitting device (PLED). High brightness and efficiency can be obtained for a PLED by using O₂-plasma treatment of the anode surface, optimized film thickness of LEP, and a calcium/aluminum based cathode. Regarding FLCP, the temperature range of the mesophase, spontaneous polarization, and response time are related to the chemical structure of the mesogenic core, the dipole-moment of the chiral center, and the mesogenic side-chain content of FLCP. FLCP exhibiting chiral smectic C phase with broad temperature range and excellent electro-optical properties can be obtained via architectural molecular design of mesogenic groups. In addition, second-order optical nonlinearity and temporal stability are related to the chromophore content and crosslinking density of soluble polyimide based organic/inorganic NLO polymers. The nonlinear optical coefficient can be enhanced by increasing chromophore content. Better temporal stability is obtained for the NLO-active interpenetrating polymer network (IPN) in comparison with those of the organic/inorganic hybrids and semi-IPN polymers.