Prevention of short circuits in solution-processed OLED devices

• Published in: Organic electronics Vol. 15; no. 6; pp. 1166 - 1172
• Main Authors: Jolt Oostra, A., Blom, Paul W.M., Michels, Jasper J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2014; Elsevier
• Subjects: Applied sciences; Design. Technologies. Operation analysis. Testing; Electronics; Exact sciences and technology; Integrated circuits; Leakage-current; Lifetime; Optoelectronic devices; PEDOT:PSS; Repair; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Sodium-hypochlorite; Sodium-hypochlorite; Lifetime; Repair; Leakage-current; PEDOT:PSS; Material processing; Direct contact; Prevention; Thiophene derivative polymer; Optoelectronic device; Defect; Growth from solution; Organic electronics; Polymer blends; Cathode; Durability; Hardware in the loop simulation; Pinhole; Failures; Contamination; Hole injection layer; Short circuit; Sodium; Interconnection; Integrated circuit; Organic light emitting diodes; Styrenesulfonate polymer; Leakage current; Reliability; Via hole
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2014.03.008

[Display omitted] •We present a highly effective method of preventing short circuits in OLEDs.•The method also proved highly effective in reducing leakage currents.•The treatment has little to no effect on the luminance of the OLED devices.•The treatment has no detrimental effect on the lifetime of the OLED devices.•We deem the repair method to be compatible with large scale production of OLEDs. Pinholes in the emitting layer of an organic light emitting diode (OLED), e.g. induced by particle contamination or processing flaws, lead to direct contact between the hole-injection layer (HIL) and the cathode. The resulting short circuits give rise to catastrophic device failure. We demonstrate that these short circuits can be effectively prevented by an oxidative treatment of the HIL with aqueous sodium hypochlorite (NaClO(aq), bleach), which locally lowers the conductivity of the HIL (i.e. poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)) by more than eight orders of magnitude while leaving the emitting layer virtually unaffected. The oxidizer treatment is evidenced by an order of magnitude reduction in leakage current and strong reduction in the number of bright spots in the emitting area, without affecting the device lifetime. Diode behavior is even recovered in deliberately flawed devices containing 80μm sized defects.