Electron injection via doped p–n heterojunction for inverted organic light emitting diodes

Abstract

In this study, inverted organic light emitting diodes (OLEDs) have been fabricated using the doped p–n heterojunction composed of poly(3,4-ethylenedioxythiophene) :poly(styrenesulfonate) (PEDOT:PSS) and lithium carbonate doped bathocuproine (Li2CO3:BCP) to provide the electron current. The field-induced charge-carrier separation at the doped organic/organic heterointerface was adopted to illuminate the process of generating electron current. Nevertheless, the performance of the inverted OLEDs remained nearly invariable when the PEDOT:PSS thickness ranged from 15 to 38 nm. This was understood mostly based on the temporary reduction of the PEDOT+ to the PEDOT0 due to the localized electron in the PSS− being repelled back to the highest occupied molecular orbital of the PEDOT+ by electrons accumulated at the cathode/PEDOT:PSS interface. The current research presents an insightful understanding of the electrical properties of an organic doped p–n junction that is reversely biased.

Charge-generation structures and their applications in light-emitting devices

“…Common n-type materials used in CGLs include transition metal oxides such as molybdenum oxide (MoO 3 ), tungsten oxide (WO x ), and zinc oxide (ZnO), and organic compounds such as tetrafluoro-tetracyano-quinodimethane (F4TCNQ) and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) [56,60,66,67,[75][76][77][78][79][80][81][82][83][84]. P-type materials include organic compounds such as 1,1-bis-(4-bis(4-methyl-phenyl)-aminophenyl)-cyclohexane (TAPC), N,N ′ -di(naphth-1-yl)-N,N ′diphenyl-benzidine (NPD), 4,4 ′ ,4 ′′ -tris(N-3-methylphenyl-Nphenylamino) triphenylamine (m-MTDATA), and polymers like poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) [28,29,52,78,85,86].…”

Flexible organic solar cell to power modern cardiac pacemakers: Versatile for all age groups, skin types and genders

“…Primary batteries have a lifespan of about six to seven years [2] with replacement rate of upto 25% [3]. Thus, organic PV cells are best suitable for stated purpose because of their suitable power production, lower fabrication price and bio-compatibility forming them best suitable technique of onsite electricity production inside the body [4][5][6]. Recently, organic photo-voltaic (OPV) devices have appealed significant attention for their commercial application primarily due to their mechanical flexibility, lower fabrication cost and semitransparent character.…”

Inverted Quantum-Dot Light Emitting Diode Using Solution Processed p-Type WOx Doped PEDOT:PSS and Li Doped ZnO Charge Generation Layer

“…In OLEDs, the methods for enhancing charge injection have been developed at organic/organic or metal/organic junctions. − One is to use alkali metal carbonates (e.g., Cs 2 CO 3 , CaCO 3 , Li 2 CO 3 and so on) as dopants in electron transporting layers (ETLs). , In this case, the Fermi level ( E F ) of an n -doped ETL shifts to the conduction band and thus increases free electron concentration at the band edge. Another one is the modification of the WF of the electrode using surface treatments such as UV-ozone, oxygen plasma and so on. − Note that the WF of the bottom electrode of an inverted QLED affects the device performance significantly.…”