Electroluminescence of SrS Thin Films Activated with Nd3+, Sm3+, Dy3+, Ho3+, and Er3+ Ions

Abstract
Thin electroluminescent SrS films activated with Nd3+, Sm3+, Dy3+, Ho3+, and Er3+ ions have been investigated. Their emission colors are found to be orange-white, orange, yellow, greenish white and green respectively, originating from transitions within the 4fn configuration of the rare-earth ions. The luminance levels of these devices are all over 200 cd/m2, except for that of SrS:Ho3+ (110 cd/m2), on the application of a driving voltage in the range 70–100 V with a frequency in the range 3 k–5 kHz. The main spectral regions of these spectra are found to shift to shorter wavelengths in comparison with those of the same ions in ZnS-based TFEL devices.