摻雜型漸進式發光層於有機發光二極體之研究

Abstract

本研究利用新製程，在一般熱蒸鍍機台上製作了具摻雜客發光體之漸進式雙主發光體結構，我們使用 NPB/Alq 3 摻雜 C545T、NPB/BAlq摻雜EY53、CBP/EPH31摻雜Ir(ppy)3這三組材料作為主發光體及客發光體，並與傳統異質接面元件、雙主發光體元件相比較，驗證了摻雜型漸進式元件能同時擁有不錯的電流效率及元件壽命。NPB/Alq3摻雜C545T之元件:摻雜型漸進式元件之電流效率滾降幅度低於雙主發光體元件，並且元件壽命為傳統異質接面元件的1.8倍;NPB/BAlq摻雜EY53之元件:在一般漸進式結構上出現了濃度焠熄效應，透過結構改良，改良之漸進式結構元件能避免犧牲電流效率，並且元件壽命提升為傳統異質接面元件的4.8倍;CBP/EPH31 摻雜 Ir(ppy) 3 之元件:使用 TCTA 作為阻擋層能改善電流效率，但卻使元件壽命下降，而摻雜型漸進式元件不需額外阻擋層，不但能擁有不錯的電流效率，並且元件壽命也有不錯的表現。

We introduced new fabrication method and a novel doped graded-dual-host emitter structure (G-EML) for OLED by utilizing a conventional research thermal-evaporation coater. NPB/Alq3 doped with C545T and NPB/BAlq doped with EY53 and CBP/EPH31 doped with Ir(ppy)3 were three pairs of host and guest materials that were selected to demonstrate the advantages of the doped graded emitting layer. By NPB/Alq3 doped with C545T: Compared with conventional bi-layer (B-EML) and mixed-emission (M-EML) structures, the current efficiency roll-off in G-EML was slower than M-EML. And the lifetime was 1.8 times than the B-EML. By NPB/BAlq doped with EY53: The concentration quenching was found in conventional G-EML device. We report an improved doped graded-emission layered structure (IG-EML) which the lifetime was 4.8 times for B-EML device and did not compromise its current efficiency. By CBP/EPH31 doped with Ir(ppy)3: Using TCTA to be the blocking layer could enhance the current efficiency, but the device lifetime would drop. The G-EML device could enhance the current efficiency without blocking layer, and the lifetime was also good.