Organic light-emitting diodes using 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane as p-type dopant

Abstract

We demonstrate that 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane (F2-HCNQ) can serve as an excellent electrical doping material for hole transport materials with the highest occupied molecular orbital level as high as 5.4 eV, such as N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB). With its relatively strong electron-accepting ability and high thermal stability, F2-HCNQ doped NPB organic light-emitting diode (OLED) showed improved power efficiency with low driving voltage. The tris(8-hydroxyquinoline)aluminum based OLED with F2-HCNQ doped NPB layer and Cs2O doped bathophenanthroline electron transport layer exhibits power efficiency of 3.6 lm/W with driving voltage of 3.2 V at 100 cd/m2.

Toward a comprehensive understanding of molecular doping organic semiconductors (review)

“…In turn, however, the low vapor pressure and potential desorption of (typically small) molecular dopants like F 4 TCNQ [134][135][136] and, in particular, their diffusion through layered structures represents an important issue that has been repeatedly addressed in literature [48,65] A c c e p t e d M a n u s c r i p t 25 stability of the systems cannot be fully assured and interfacial effects between substrate and dopant can mimic doping related energy-level shifts [48].…”

Comparison of solution-mixed and sequentially processed P3HT:F4TCNQ films: effect of doping-induced aggregation on film morphology

“…[20][21][22][23][24] Several groups have synthesized and studied alternative molecular dopants in an effort to increase the thermal stability of doped films. 21,[25][26][27][28][29][30][31][32] Finally, a less commonly discussed but equally problematic issue lies in solution processing doped films. Several groups have noted that doping often results in drastically reduced solubility of polymers; as a result, mixed polymer:dopant solutions must be kept at high temperatures and dilute concentrations, and tend to rapidly aggregate, forming gels or large particles.…”

Ground-State Electronic Structure in Charge-Transfer Complexes Based on Carbazole and Diarylamine Donors

“…Our calculations show that this complex has a Mulliken charge on F 4 -TCNQ of 0.306 |e|. In the case of NPB, 11 Mi et al found that, although there was improved current density, the efficiency decreased with F 4 -TCNQ dopants. When using F 2 -HCNQ as a dopant, then both current density and efficiency increased.…”