The performance of the blue perovskite light-emitting
diodes (PeLEDs)
is limited by the low photoluminescence quantum yields (PLQYs) and
the unstable emission centers. In this work, we incorporate sodium
bromide and acesulfame potassium into a quasi-2D perovskite to control
the dimension distribution and promote the PLQYs. Benefiting from
the efficient energy cascade channel and passivation, the sky-blue
PeLED has an external quantum efficiency of 9.7% and no shift of the
electroluminescence center under operation voltages from 4 to 8 V.
Moreover, the half lifetime of the devices reaches 325 s, 3.3 times
that of control devices without additives. This work provides new
insights into enhancing the performance of blue PeLEDs.
Integrating highly efficient photovoltaic (PV) function into light‐emitting diodes (LEDs) for multifunctional display is of great significance for compact low‐power electronics, but it remains challenging. Herein, it is demonstrated that solution engineered perovskite nanocrystals (PNCs, ≈100 nm) enable efficient electroluminescence (EL) and PV performance within a single device through tailoring the dispersity and interface. It delivers the maximum brightness of 490 W sr−1 m−2 at 2.7 V and 23.2% EL external quantum efficiency, a record value for near‐infrared perovskite LED, as well as 15.23% PV efficiency, among the highest value for nanocrystal perovskite solar cells. The PV–EL performance is well in line with the reciprocity relation. These all‐solution‐processed PV‐LED devices open up viable routes to a variety of advanced applications, from touchless interactive screens to energy harvesting displays and data communication.
The rolling‐off phenomenon of device efficiency at high current density caused by quenching of luminescence in perovskite light‐emitting diodes (PeLED) is challenging to be solved. Here, 2‐amino‐5‐iodopyrazine (AIPZ) is dissolved in a mixed solvent of chlorobenzene (CB)/isopropanol (IPA) (7:3 volume ratio) for surface post‐treatment of FAPbI3 perovskite film. The interaction of AIPZ and perovskite surface not only balances the charge injection but also passivates defects to enhance radiative recombination in PeLED. Therefore, the PeLED champion yields peak external quantum efficiency reaching 23.2% at the current density of 45 mA cm−2 with a radiance brightness of 290 W sr−1 m−2. More importantly, the rolling‐off of device efficiency is significantly reduced. The lowest rolling‐off devices can maintain 80% of peak EQE (22.1%) at a high current density of 460 mA cm−2, whereas the control device only retains 25% of the peak EQE value. This work provides an effective strategy to improve performance and reduce the EQE rolling‐off of PeLED for practical application.
It is technically challenging to reversibly tune the layer number of 2D materials in the solution. Herein, a facile concentration modulation strategy is demonstrated to reversibly tailor the aggregation state of 2D ZnIn2S4 (ZIS) atomic layers, and they are implemented for effective photocatalytic hydrogen (H2) evolution. By adjusting the colloidal concentration of ZIS (ZIS‐X, X = 0.09, 0.25, or 3.0 mg mL−1), ZIS atomic layers exhibit the significant aggregation of (006) facet stacking in the solution, leading to the bandgap shift from 3.21 to 2.66 eV. The colloidal stacked layers are further assembled into hollow microsphere after freeze‐drying the solution into solid powders, which can be redispersed into colloidal solution with reversibility. The photocatalytic hydrogen evolution of ZIS‐X colloids is evaluated, and the slightly aggregated ZIS‐0.25 displays the enhanced photocatalytic H2 evolution rates (1.11 µmol m−2 h−1). The charge‐transfer/recombination dynamics are characterized by time‐resolved photoluminescence (TRPL) spectroscopy, and ZIS‐0.25 displays the longest lifetime (5.55 µs), consistent with the best photocatalytic performance. This work provides a facile, consecutive, and reversible strategy for regulating the photo‐electrochemical properties of 2D ZIS, which is beneficial for efficient solar energy conversion.
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