Metal deposition for optoelectronic devices using a low vacuum vapor phase deposition (VPD) system

Abstract

A vapor phase deposition (VPD) system has been used to deposit magnesium and zinc films and prepare optoelectronic devices under low vacuum conditions, i.e. 1 torr. An analysis of the metal films via SEM, AFM, XRD and four-point probe resistivity measurements revealed comparable characteristics to metal films deposited in a vacuum thermal evaporation (VTE) system. Magnesium cathodes were fabricated for organic light emitting diodes (OLEDs) and organic photovoltaic (OPV) devices. OLEDs were fully made in either the VPD or VTE system employing aluminum tris-(8 hydroxyquinoline) [Alq3] as the green fluorescent emitter or fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] as the green emitting phosphor. Analysis of the OLED devices made in the VPD system showed external quantum efficiencies (EQE = 0.9 ± 0.1%) and (EQE = 7.6 ± 0.6%) at a luminance of 100 cd/m2for the fluorescent and phosphorescent devices, respectively. In addition, organic photovoltaics (OPVs) were fully fabricated by both methods employing copper phthalocyanine (CuPc) and C60as the donor/acceptor materials. Analysis of the OPV devices made in the VPD system showed a power efficiency of 0.5 ± 0.1%, an open circuit voltage of 0.45 ± 0.05% and a fill factor of 0.50 ± 0.05%.