Great improvement of operation-lifetime for all-solution OLEDs with mixed hosts by blade coating

Abstract

We investigated some effective device designs and fabrication methods for long operation-lifetime all solution-processed Phosphorescent OLEDs (PhOLEDs) and fluorescent OLEDs with mixed-hosts system and thin Poly [(9, 9-dioctylfluorenyl-2, 7-diyl)-co-(4, 4\'-(N-(4-sec-butylphenyl) diphenylamine)] (TFB). The all-solution-processed green PhOLEDs had high current efficiency (30.3 cd/A) and long operation lifetime. The best half-lifetime of green PhOLEDs with thin HTL, MH-hosts EML and optimized deposition was 310 h at an initial luminance 1000 cd/m(2), 250 h at an initial luminance 500 cd/m(2) for green PhOLEDs with thin HTL, and MH-hosts EML, and the lifetime of triple layer PhOLEDs device was only 0.5 h for the same materials. The red PhOLEDs exhibited a high current efficiency (10.93 cd/A) and half lifetime with 157.9 h at an initial luminance 500 cd/m(2). For the blue fluorescent OLEDs, the thin polymer TFB, mixed-hosts EMI, double EMLs and optimization deposition yield a high current efficiency (5.68 cd/ A) and long operation-lifetime with 117.7 h at an initial luminance 500 cd/m(2). Single host fluorescent device had half-lifetime of 73.5 h only at an initial luminance 100 cd/m(2). Finally, by doping red emitter Rubrene into stable blue device, we achieved soft yellow OLEDs with high efficiency (10.87 cd/A) and 8 fold improvement operation-lifetime (1200 h). We believe that such all-solution-processed OLEDs which showed greatly improved operational lifetimes would be suitable for the indoor supportive lighting with natural colors. (C) 2016 Elsevier B.V. All rights reserved.