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Current transport and aging in direct‐current powder electroluminescent display devices
Author(s) -
Raposo Joseph A.,
Singh Vijay P.,
McClure John C.,
Bell Raymond G.,
Mayo Jonathan W.
Publication year - 1993
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1889/1.1984893
Subject(s) - materials science , electroluminescence , optoelectronics , phosphor , layer (electronics) , thin film , direct current , degradation (telecommunications) , electrode , current (fluid) , composite material , voltage , electrical engineering , nanotechnology , chemistry , engineering
— Direct‐current powder electroluminescent (DCPEL) display devices were excited by unipolar voltage pulses, and current flow through the phosphor was recorded. Devices with different formed layer thicknesses were obtained by varying the forming voltage. For a fixed electric field in the formed layer, the phosphor current did not show a substantial increase as the thickness of the formed layer increased. A model is proposed in which tunnel injection from the p‐Cu 2 S/i‐ZnS:Mn interface of a reverse‐biased p‐Cu 2 S/i‐ZnS:Mn/n‐SnO 2 structure is thought to be the controlling current mechanism. Aging studies revealed that further forming is the dominant degradation mechanism in the early stages, while load‐line degradation and softening become the dominant degradation modes as the aging process is continued. The conventional DCPEL device structure was modified by introducing a thin chromium layer just prior to the deposition of the aluminum back electrode. Incorporating chromium reduced the initial series resistance of the device. A hybrid device employing a thin film (1 μm) of ZnS:Mn, sandwiched between two thin dielectric layers (5 nm), was fabricated; ZnS:Mn,Cu powder was sprayed onto the thin‐film sandwich. The hybrid structure showed good luminance without forming; however, device degradation with time was still present.