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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