Single-layer organic electroluminescent devices by vapor deposition polymerization

Abstract

A novel method is presented herein regarding the preparation of a single-layer organic electroluminescent (EL) polymer thin film device. The device was made by simultaneously co-depositing two polymer thin film forming monomers, a hole-transporting molecule triphenyldiamine derivative (TPD) and an EL active molecule 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) on an indium-tin-oxide (ITO) glass substrate. The device structure was composed of the ITO glass, the TPD, and TPB co-doped polymer thin film, and a thermally evaporated aluminum electrode. Carrier injection from the two electrodes was significantly observed and the blue light in EL spectra, with an emission maximum at 435 nm, was triggered at a driving voltage of 17 V.

Polarized Absorption, Spontaneous and Stimulated Blue Light Emission of J‐type Tetraphenylbutadiene Monocrystals

“…These contribute to the broad emission and to the shoulder at about 2.75 eV observed in the cw spectra. We point out that the PL data reported in the literature [18][19][20][21][22][23][24] do not allow distinguishing between the intrinsic emissions and the emission from defect states, the observed PL being typically unpolarized, relatively broad, and centred between about 2.7 and 2.8 eV, depending on the sample.…”

“…[22,23] Furthermore, it can be deposited in thin film form on different substrates. [18][19][20][21][22] The photoluminescence (PL) properties of the TPB molecules in solution and in optically transparent polymeric matrices have been investigated both experimentally [24] and theoretically, [25] and the emission spectrum of TPB-based devices is reported by many authors, with maximum typically found at 2.7-2.8 eV and relatively high emission quantum yield. [18,19,21,23,24] Interestingly for both applications and for the comprehension of the intrinsic properties, TPB forms single crystals.…”

“…[18][19][20][21][22] The photoluminescence (PL) properties of the TPB molecules in solution and in optically transparent polymeric matrices have been investigated both experimentally [24] and theoretically, [25] and the emission spectrum of TPB-based devices is reported by many authors, with maximum typically found at 2.7-2.8 eV and relatively high emission quantum yield. [18,19,21,23,24] Interestingly for both applications and for the comprehension of the intrinsic properties, TPB forms single crystals. However, most of the reported optical measurements are for TPB polycrystalline films, which are mainly limited to emission [18,19,21,23,24] and with little discussion on the origin of the observed transitions.…”

“…[18,19,21,23,24] Interestingly for both applications and for the comprehension of the intrinsic properties, TPB forms single crystals. However, most of the reported optical measurements are for TPB polycrystalline films, which are mainly limited to emission [18,19,21,23,24] and with little discussion on the origin of the observed transitions.…”

“…[15][16][17] Among the many organic semiconductor systems, 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) (molecular structure in Figure 1) is a well-known, highly emissive molecule, which is attracting wide attention as an electro-active molecule. It is often used as blue electroluminescent dye [18][19][20][21] or as highenergy emitter in organic white-light emitting devices. [22,23] Furthermore, it can be deposited in thin film form on different substrates.…”