Buffer-modified C₆₀/pentacene as organic charge generation layer based on Al and MoO₃

Abstract

We demonstrate tandem organic light-emitting diodes (TOLEDs) with excellent performance using Al and MoO₃ buffer-modified C₆₀/pentacene as charge generation layer (CGL). Al and MoO₃ were used as the electron and hole injection layers of C60/pentacene CGL, respectively. Green phosphorescence TOLEDs with the structure of ITO/NPB/mCP:Ir(ppy)₃/TPBi/Al/C₆₀/pentacene/MoO₃/NPB/mCP:Ir(ppy)₃/TPBi/Cs₂CO₃/Al were fabricated. The results show that the inserted Al and MoO₃ can effectively increase the charge injection capacity of organic CGL, resulting the improvement of luminance and current efficiency of TOLEDs. The turn-on voltage of TOLEDs is much lower than that of single-unit device, and the current efficiency is more than 2 times larger than that of the single-unit device. TOLEDs can exhibit excellent photoelectric performance when the thicknesses of Al, C₆₀, pentacene and MoO₃ are 3 nm, 15 nm, 25 nm and 1 nm, respectively. The maximum luminance and current efficiency are 7 920.0 cd/m² and 16.4 cd/A, respectively. This work is significant to build new CGL structures for realizing high-performance TOLEDs.

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This work has been supported by the National Natural Science Foundation of China (No.61604027), the Basic and Advanced Technology Research Project of Chongqing Municipality (Nos.cstc2016jcyjA0272 and cstc2016jcyjA2063), the Scientific and Technological Research Foundation of Chongqing Municipal Education Commission (Nos.KJ1500424 and KJ1600418), and the Youth Natural Science Foundation of Chongqing University of Posts and Telecommunications (No.A2013-39).