Blue Emission Mechanism of NPB/ZnSe Hybrid Structure

Abstract

The electrical and optical properties of organic-inorganic hybrid light emitting diodes (HLED) have been investigated. The HLED is consisted of organic material N,N'-di(naphthalene-l-yl)-N,N'- diphenyl-benzidine (NPB) as a hole transport layer and inorganic material zinc selenide (ZnSe) as an electron transport layer and emitting layer as well. The electrical and optical properties have been characterized by current-voltage measurement and electroluminescence (EL) spectroscopy, respectively. The current of HLED decreases with increasing ZnSe thickness, while the threshold voltage increases. The EL spectrum exhibits two peaks at 457 nm and 500 nm, due to electron-hole recombination from energy gap of ZnSe and recombination from defect states in ZnSe layer, respectively. The emission mechanism is described by electric field in organic and inorganic layers.