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Interface Effect on Efficiency Loss in Organic Light Emitting Diodes with Solution Processed Emitting Layers
Author(s) -
Ho Szuheng,
Chen Ying,
Liu Shuyi,
Peng Cheng,
Zhao Dewei,
So Franky
Publication year - 2016
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201600320
Subject(s) - oled , materials science , optoelectronics , photoluminescence , diode , interface (matter) , quantum efficiency , layer (electronics) , excimer , efficient energy use , nanotechnology , optics , fluorescence , contact angle , composite material , physics , electrical engineering , engineering , sessile drop technique
The performance of multilayered OLEDs with a solution processed emitting layer (EML) is compared to that of counterparts with an evaporated EML and it is found that the interfacial energy changes at the EML and electron transport layer (ETL) interface is a key factor determining the device efficiency. From the results of exciplex photoluminescence emission at the EML/ETL interface and energetic disorder measurements, it is revealed that there is an energy shift in the solution processed EML along with a band tail broadening compared with the device with an evaporated EML, resulting in inefficient hole blocking at the EML/ETL interface and a decrease in device efficiency. Using an ETL with a deep highest occupied molecular orbital (HOMO) level can ameliorate this problem, resulting in a solution processed OLED with a high external quantum efficiency of 29%.