Here, we report efficient and stable indium phosphide (InP) based inverted red quantum dot light-emitting diodes (QLEDs) using a new high mobility and deep HOMO level hole transport layer (HTL) and an optimized sol−gel ZnMgO layer. A new hole transport material, DBTA, containing rigid dibenzothiophene and tertiary amine units has been designed with high hole mobility and a deep HOMO level to inject holes faster into the InP-QDs. Also, to decrease the electron transporting property of the ZnMgO NPs, a sol−gel ZnMgO layer with optimum magnesium content (17%), low-temperature annealing (180 °C), and a selfaging process is used on the transparent electrode. The high mobility DBTA and an optimized sol−gel Zn 0.83 Mg 0.17 O layer with the self-aging process are responsible for achieving good charge balance and suppressing nonradiative losses in InP-QLED. The fabricated QLED with DBTA and optimized sol− gel Zn 0.83 Mg 0.17 O exhibited an external quantum efficiency of 21.8%, current efficiency of 23.4 cd/A, and operating lifetime (LT 50 ) of 1095 h at 1000 cd/m 2 .
Here, we report an
efficient inverted red indium phosphide (InP)
comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting
diode (QLED) by modulating an interfacial contact between the electron
transport layer and emissive InP-QDs and applying self-aging approach.
The red InP-QLED with optimized interfacial contact exhibits a significant
improvement in maximum external quantum efficiency and current efficiency
from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days
of self-aging, which is an almost 2.3-fold improvement compared to
the fresh device. The analysis indicates the consecutive reduction
in electron injection and accumulation in the emissive QD due to changes
in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage)
through a downward vacuum-level shift according to the aging times.
During the device aging periods, the oxygen vacancy of ZnMgO reduces,
which leads to lower the conductivity of ZnMgO. As a result, charge
balance of the device is improved with the suppression of exciton
quenching at the interface of ZnMgO and InP-QD.
The efficiency and device lifetime of quantum dot light-emitting diodes (QLEDs) devices suffer due to charge unbalance issue resulting from excess electron injection from ZnO electron transport layer (ETL) to...
We report high-efficiency and long-lifetime inverted green cadmium-free (InP-based) quantum dot light-emitting diodes (QLEDs) using a stable ZnO/ZnS cascaded electron transport layer (ETL). We have successfully developed a strategy to spin-coat stable ZnS ETLs with a relatively higher conduction band minimum (CBM) and lower electron mobility than that of ZnO, which leads to balanced carrier injection and an improved device lifetime. Analysis shows that by using the ZnO/ZnS cascaded ETL, electron injection is reduced, resulting in an improved charge balance in the QD layer and suppressed exciton quenching, which preserves the emission properties of QDs. Optimized devices with ZnO/ZnS cascaded ETLs show a maximum external quantum efficiency of 10.8% and a maximum current efficiency of 37.5 cd/A; these efficiency values are an almost 2.2-fold improvement compared to those of reference devices without ZnS. The QLED devices also showed a remarkably long lifetime (LT 70 ) of 265 h at an initial luminance of 1000 cd/m 2 . The predicted half-lifetime (LT 50 ) at 100 cd/m 2 is 60,255 h, which, to our knowledge, is currently the longest lifetime yet reported for InP-based green QLEDs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.