Science news: 2022 ADVANCED MATERIALS (IF 32.086): Achieving 15.4% EQE! How to achieve high efficiency with the addition of 2-phenethylammonium iodide (PEAI)?
The performance of perovskite quantum dots (QDs) and QD-based light-emitting diodes (QLEDs) has been greatly improved in recent years, with electroluminescence (EL) efficiencies exceeding 20% for green and red emission.
However, the development of perovskite near-infrared (NIR) QLEDs has stalled, and the maximum EL efficiency is still below 6%, thus limiting their further applications.
ADVANCED MATERIALS (IF 32.086) publishes a study in March 2022. The research team developed new NIR-emitting FAPbI3 QDs by post-processing the long alkyl-encapsulated QDs with 2-phenethylammonium iodide (PEAI).
The addition of PEAI reduces QD surface defects, thereby providing high photoluminescence quantum yields up to 61.6%. A n-octane solution of PEAI-passivated FAPbI3 QDs was spin-coated on top of a PEDOT:PSS-treated ITO electrode modified with a thermally cross-linked hole transport layer to provide full coverage, smooth and dense QDs film.
Combined with CN-T2T, an efficient electron transport material with deep lowest unoccupied molecular orbitals and good electron mobility, the best device with EL λmax at 772 nm achieves up to 15.4 % at a current density of 0.54 mA cm−2 (2.6 V) which is the highest efficiency reported so far for perovskite-based NIR QLEDs.
This study provides a facile strategy to fabricate high-quality perovskite QD films suitable for high-efficiency NIR QLED applications.
Figure 1. Coverage rate of FAPbI3 QDs coated on (a) PVK, (b) polyTPD, and (c) VB-FNPD films.
Fig. 2. Absorbance of PVK, polyTPD, and VB-FNPD films before and after washing with n-octane for retention test. Each film was prepared using a concentration of 4 mg/mL by dissolving in the solvents (CHO for VB-FNPD, and CB for PVK and polyTPD) and spin-coated at 2000 rpm for 1 min on quartz substrates. After annealing (VB-FNPD at 100 °C for 5 min and 170 °C for 30 min; PVK and poly-TPD at 100 °C for 5 min), the absorbances of the samples were measured for the first time, after which 20 μL of octane was dripped on the films while spinning at 12000 rpm. After spinning for 15s, the absorbance was measured for the second time.
Fig. 3. Operational lifetimes of Device at different initial radiant emittance, 60, 30, and 10 mW m−2 under a constant current density.
Keywords: （NIR）QLED , perovskite QD films