Open Access Nano Express

Electrospray deposition of polymer thin films for organic light-emitting diodes

Wontae Hwang1, Guoqing Xin1, Minjun Cho1, Sung Min Cho1 and Heeyeop Chae2*

Author affiliations

1 School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, South Korea

2 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon, 440-746, South Korea

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Citation and License

Nanoscale Research Letters 2012, 7:52  doi:10.1186/1556-276X-7-52

Published: 5 January 2012

Abstract

Electrospray process was developed for organic layer deposition onto polymer organic light-emitting diode [PLED] devices in this work. An electrospray can be used to produce nanometer-scale thin films by electric repulsion of microscale fine droplets. PLED devices made by an electrospray process were compared with spin-coated ones. The PLED device fabricated by the electrospray process showed maximum current efficiency of 24 cd/A, which was comparable with that of the spin-coating process. The electrospray process required a higher concentration of hole and electron transport materials in the inks than spin-coating processes to achieve PLED maximum performance. Photoluminescence [PL] at 407 nm was observed using electrosprayed poly(N-vinyl carbazole) films, whereas a peak at 410 nm was observed with the spin-coated ones. Similar difference in peak position was observed between aromatic and nonaromatic solvents in the spin-coating process. PLED devices made by the electrospray process showed lower current density than that of spin-coated ones. The PL peak shift and reduced current of electrosprayed films can therefore be attributed to the conformation of the polymer.

Keywords:
organic light-emitting diodes; electrospray, polymer, conformation.