Investigations of solution-processed charge generation unit with low concentration of small molecule doped in p-type/HAT-CN6 for tandem OLED

• Published in: Journal of luminescence Vol. 169; pp. 61 - 64
• Main Authors: Talik, N.A., Yeoh, K.H., Ng, C.Y.B., Tan, C.Y., Yap, B.K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2016
• Subjects: Charge generating layer; Electrical measurement; Energy band diagram; Solution processable; Electrical measurement; Charge generating layer; Solution processable; Energy band diagram
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2015.08.048

We investigated the charge generation and injection mechanism in solution processed charge generation unit (CGU) used in our high performance tandem organic light emitting diode (OLED) via capacitance–voltage (C–V) and current density–voltage (J–V) measurements. By doping 2wt% of small molecule 1,1-bis-(4-bis(4-tolyl)-aminophenyl) cyclohexene (TAPC) into Poly (N-vinylcarbazole) (PVK) as p-type layer of the CGU, we obtained more than two folds improvement in the tandem device efficiency compared to single device. The performance improvement of the TAPC doped CGU could be attributed to low built-in potential, large vacuum level shift as well as high charge density for efficient charge generation. •Charge-generation and injection mechanism in CGU for tandem OLED is investigated.•Small molecule, TAPC doped in p-type/HAT-CN6 has been used for tandem OLED.•The improvement attributes to the lower Vbi and larger ΔVL in doped layer.•Narrower W and high carrier density also contribute to efficiency improvement.