Efficient tandem organic light-emitting device based on photovoltaic-type connector with positive cycle

Abstract

We designed a tandem organic light-emitting device based on an organic photovoltaic-type charge generation connector (CGC) of fullerene carbon 60/copper(II) phthalocyanine. The CGC can absorb a portion of photons radiated from emission zone and form excitons which disassociated into free charges at PN junction interface without energy barrier, leading to low driving voltage and better charge balance. The efficiency increases remarkably with increasing current density, even beyond two folds compared with single unit device under higher current density, meaning slower roll-off. The whole process is a positive cycle, and actually enhances the utilization of internal radiation and the overall performance of tandem device.

Tandem Organic Light‐Emitting Diodes

“…Most investigations on tandem OLEDs have been done related to the compositions of the intermediate connectors and mainly focus on their electronic properties . The intermediate connector can be formed using: i) inorganic/inorganic layers, ii) organic/inorganic layers, or iii) organic/organic layers …”

“…The n‐type dopant is an alkali metal or alkaline earth metal, such as Li, Rb, Cs, or Mg, as mentioned above. The p‐type dopant can be a strong oxidizing agent, such as FeCl 3 , F 4 ‐TCNQ, WO 3 , or MoO 3 . Their combinations can be Alq 3 :Li or TPBI:Li/NPB:FeCl 3 , Alq 3 :Li/NPB:F 4 ‐TCNQ, Alq 3 :Mg/m‐MTDATA:F 4 ‐TCNQ, Bphen:Cs 2 CO 3 /NPB:WO 3 , Alq 3 :Mg/NPB:WO 3 , Alq 3 :Li/2‐TNATA:MoO 3 , Alq 3 :Mg/PTCDA:MoO 3 , and TPBI:Li 2 CO 3 /C60/pentacene/TCTA:MoO 3 .…”

“…The transparency and the thickness of the connector affect the light output of the device. Therefore, many studies have been carried out on the construction of the intermediate connectors . However, a systematic understanding of the mechanism of the intermediate connectors and how to form ideal intermediate connectors in the devices is very much needed in order to facilitate further studies of high‐performance tandem OLEDs.…”

P-95: Inverted Tandem Architecture of Quantum-dot Light Emitting Diodes with Solution Processed Charge Generation Layers

“…Generally, organic-organic, organic-metal or metal-metal oxide bilayers can be used as CGLs. [14][15][16][17][18][19] However, unfortunately, these thermal evaporation method to form the efficient CGL cannot be adopted into tandem QLED because of the solution processing of QDs on top of CGL. The solution process can damage and wash-out a thermal evaporated CGL.…”

20.4:Distinguished Paper: Quantum‐dot Light Emitting Diodes with Charge Generation Layers

“…Thermally deposited organic charge generation layers (CGLs) has been used to overcome the limitation of substrate [19]. However, thermal deposition method does not match to largearea process due to high-cost and metal mask warp.…”