具延伸共軛系統受體的高效率深紅及近紅外光螢光材料之合成與研究

Abstract

在本論文中，我們策略性地合成了一系列以供體-受體-供體為系統且不含金屬的有機發光團NTz-TPA、NOz-TPA、NOz-DPA以及NOz-t-TPA，其中，作為受體的NTz和NOz具有延伸共軛系統及優異的平面性，提供了強烈的光學躍遷和狹窄的能隙。因此目標產物皆為有突出螢光量子產率的深紅色至近紅外放光的有機發光材料：在甲苯溶液中，得到放光波長在618-661 nm，量子效率~100%；在固體薄膜中，則可得到放光波長在650-715 nm，量子效率6-22%。將此系列發光材料作為客體，應用在有機發光二極體元件時，可得一系列高效率紅光至近紅外光的器件結果。其中又NOz-t-TPA表現最為優異，若將DTAF:3P-T2T做為主體，可得到放光波長700 nm的近紅外光螢光且外部量子效率可達4.0%，而若將主體改為TrisPCz:CN-T2T，放光位置紅移至710 nm且外部量子效率進一步提升至6.6%，此效率在已知的近紅外光有機螢光發光材料中為最佳效率之一。

A series of metal-free organic emitting chromophores NTz-TPA, NOz-TPA, NOz-DPA, and NOz-t-TPA with an electron donor-acceptor-donor (D-A-D) configuration were strategically designed and synthesized. Featuring an extended pi-conjugated system and excellent planarity, the acceptors naphthobisthiadiazole (NTz) and naphthobisoxadiazole (NOz) provide a strong optical transition and narrowed energy gap. All compounds exhibit intense red to near infrared (NIR) fluorescence with peak wavelength 618-661 nm, ~100% emission quantum yield in toluene and 650-715 nm with 6-22% emission quantum yield in solid thin film. The doped OLED based on 5 wt% NOz-t-TPA with DTAF:3P-T2T as the cohost system exhibits remarkable NIR fluorescence with external quantum efficiency (EQE) of 4.0% at 700 nm. Replacement with TrisPCz:CN-T2T as cohost doped with 10 wt% NOz-t-TPA makes further improvement of EQE to 6.6% at 710 nm, which is among the best records for the fluorescent NIR OLEDs around 710 nm.