Simplified phosphorescent organic light-emitting diodes with a WO3-doped wide bandgap organic charge transport layer

Effects of Localized Heating at Heterointerfaces on the Reliability of Organic Light-Emitting Diodes

“…Suitable p-type dopants for wide bandgap CBP include transition metal oxides such as MoO 3 , and WO 3 which have a large electron affinity above 6.0 eV [9]. Our recent study has confirmed the effectiveness of WO 3 doping in CBP when the doping level is greater than 10mol% [9]. It has also been found that to facilitate hole injection, the doped layer thickness needs to be greater than 5 nm.…”

“…This would facilitate hole injection through tunneling, and effectively reduce the overall hole injection barrier. Suitable p-type dopants for wide bandgap CBP include transition metal oxides such as MoO 3 , and WO 3 which have a large electron affinity above 6.0 eV [9]. Our recent study has confirmed the effectiveness of WO 3 doping in CBP when the doping level is greater than 10mol% [9].…”

“…An alternative method for reducing voltage drop at the ITO/HTL interface is to dope the organic HTL material with p-type dopants [9], [10]. Excess holes cause a downward shift of the Fermi level in the HTL toward its HOMO edge [10], resulting in a depleted region whose width decreases with increasing doping concentration.…”

“…The resulting products from these processes may screen the local electric field or act as nonradiative recombination centers and luminescence quenchers [5]- [7]. All these processes can be thermally enhanced and accelerated by joule heating under high current injection [8], [9]. Therefore, current-induced thermal effects, which are particularly pronounced at localized regions like heterointerfaces where a large voltage drop exists, may greatly accelerate the degradation of OLEDs.…”

Effects of PEDOT:PSS:GO composite hole transport layer on the luminescence of perovskite light-emitting diodes

“…[1][2][3][4][5] A hole transport layer (HTL) is essential for the injection and transport of holes, which affects the number of holes in the region of the emission layer (EML), and correspondingly the radiative exciton recombination. [6][7][8][9] Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) is a widely utilized HTL in PeLEDs, because the surface roughness of ITO and the injection barrier for holes can be reduced aer inserting PEDOT:PSS between ITO and perovskite EML. However, because PEDOT:PSS is metallic and the excitons in perovskite materials possess long diffusion length, the quenching of excitons oen happens at the interface between PEDOT:PSS and perovskite EML through nonradiative energy transfer and/or exciton dissociation pushed by the big discrepancy of energy levels between PEDOT:PSS and perovskite.…”