The performance of perovskite light-emitting diodes (PeLEDs) has progressed rapidly in recent years, with electroluminescence efficiency now reaching 20%1,2,3,4,5,6,7,8,9,10,11,12. However, devices, so far, have featured small areas and usually show notable variation in device-to-device performance. Here, we show that the origin of suboptimal device performance stems from inadequate hole injection, and that the use of a hole-transporting polymer with a shallower ionization potential can improve device charge balance, efficiency and reproducibility. Using an ITO/ZnO/PEIE/FAPbI3/poly-TPD/MoO3/Al device structure, we report a 799 nm near-infrared PeLED that operates with an external quantum efficiency (EQE) of 20.2%, at a current density of 57 mA cm−2 and a radiance of 57 W sr−1 m−2. The standard deviation in the device EQE is only 1.2%, demonstrating high reproducibility. Large-area devices measuring 900 mm2 operate with a high EQE of 12.1%, and are shown to suit medical applications such as subcutaneous deep-tissue illumination and heart rate monitoring.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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We are grateful to H. Kuan for assistance with UPS measurements. We thank C. Xie for assistance with SEM imaging. We are grateful for funding support from the Ministry of Education of Singapore (R-143-000-674-114 and R-143-000-691-114) and the National University of Singapore (R-143-000-639-133, R-143-000-A10-133 and R-143-000-A54-118).
The authors declare no competing interests.
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Absorbance (black) and photoluminescence spectra (red) of FAPbI3 perovskite.
a, Scanning electron microscopy (SEM) image and b, atomic force microscopy (AFM) image of FAPbI3 perovskite layer on device substrate.
a, Combined current density vs. voltage (black) and radiance vs. voltage (red) plots of ITO/ZnO/PEIE/FAPbI3/TFB/MoO3/Al PeLED. b, External quantum efficiency vs. current density of PeLED. Inset shows the histogram of the efficiencies of 40 devices.
Lifetime plot of 900 mm2 ITO/ZnO/PEIE/FAPbI3/Poly-TPD/MoO3/Al PeLED at constant current density of 10 mA cm−2.
a, Combined current density vs. voltage (black) and radiance vs. voltage (red) plots of 900 mm2 ITO/ZnO/PEIE/FAPbI3/TFB/MoO3/Al PeLED. b, External quantum efficiency vs. current density of 900 mm2 PeLED.
a, Combined current density vs. voltage (black) and radiance vs. voltage (red) plots of 900 mm2 ITO/ZnO/PEIE/FAPbI3/Poly-TPD/MoO3/Al PeLED on flexible PET. b, External quantum efficiency vs. current density of 900 mm2 PeLED on flexible PET.
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Zhao, X., Tan, Z. Large-area near-infrared perovskite light-emitting diodes. Nat. Photonics (2019) doi:10.1038/s41566-019-0559-3