Balanced Charge‐Carrier Transport and Defect Passivation in Far‐Red Perovskite Light‐Emitting Diodes

Abstract

Perovskites are promising light emitters that can cover broad‐range emissions over the entire visible spectrum. However, few studies have focused on uncommon wavebands, such as far‐red emission of 700–750 nm that has broad applications in biology, horticulture lighting, optogenetics, etc. Here, a strategy is demonstrated to achieve high‐performance far‐red perovskite light‐emitting diodes (PeLEDs) through antisolvent engineering. First, 1,3,5‐tris(1‐phenyl‐1H‐benzimidazole‐2‐yl) benzene (TPBi) is introduced into n‐i‐p perovskite matrix not only to passivate the defects but also to balance carrier mobility as well as adjust the energy level alignment between perovskite and the electron transport layer. The n‐type TPBi can prevent hole carriers’ movements in perovskite light emitters and enhance electron injection. Furthermore, the incorporation of TPBi uplifts the Fermi energy level of perovskites by 0.32 eV as well as diminishes the conduction band offset between zinc oxide (ZnO) and the perovskite emitters, hence alleviating the accumulation of charges at the interface. Consequently, the PeLEDs with TPBi‐modified perovskite emitters show an invariable far‐red emission peak at around 735 nm with a champion external quantum efficiency of 14.22%. This work makes up the far‐red emission of perovskite light‐emitting devices and boosts latent capacity of PeLEDs for future application.

Alkoxysilane‐Treated SnO2 Interlayer for Energy Band Alignment of SnO2 Electron Injection Layer in Inverted Perovskite Light‐Emitting Diodes

“…where J D , L, ℇ, ℇ 0 , and V are the current density, the thickness of the perovskite layer, the relative dielectric constant, [46] vacuum permittivity, and the applied voltage in the SCLC region, respectively. [47] Figure 3d and Table S4 (Supporting Information) demonstrate that the control device exhibits imbalanced charge injection, where electron injection from the SnO 2 is faster than hole injection. This indicates that electrons could accumulate at the interface between the perovskite and HIL, thus causing electron leakage through HIL.…”

A Crystalline 2D Fullerene‐Based Metal Halide Semiconductor for Efficient and Stable Ideal‐bandgap Perovskite Solar Cells

“…To quantify the change in carrier mobility in thin films, we utilized the Mott‐Gurney law based on the SCLC curves: $$$$\begin{equation}\mu \ = \frac{{8{{d}^3}J}}{{9{{\varepsilon }_0}{{\varepsilon }_{\mathrm{r}}}{{V}^2}}}\ \end{equation}$$$$where J and V are the current and open voltage, respectively, in the SCLC region. [ 57 ] After calculation, as shown in Figure 4f, the electron mobility was enhanced from 3.27 × 10 −3 to 4.43 × 10 −3 cm 2 V −1 s −1 by making use of C 60 ‐2NH 3 , which mitigated the accumulation of charge at the interface and facilitated the transfer of electrons. [ 58 ] This improvement can be simply attributed to the fact that the addition of C 60 ‐2NH 3 reduces the defects on the perovskite surface, suppresses non‐radiative recombination, improves film quality, and facilitates carrier transport.…”

Modulated Crystallization and Carrier Transport Properties for Green Perovskite Light-Emitting Diodes via Thermally Activated Delayed Fluorescent-Modified Hole Transport Layers

“…In recent years, quasi-2D metal halide perovskite materials have demonstrated outstandingly distinct advantages such as high photoluminescence quantum yields, great color purity (half-peak width of 20 nm), and tunable bandgap (light encompassing the full visible), all while remaining low in cost and simple to handle. – These exceedingly distinctive characteristics have propelled research in light-emitting diodes (LEDs), – solar cells, , and photovoltaic monitors . It is worth mentioning that LEDs have made enormous advances in terms of device luminescence, stability, and external quantum efficiency (EQE).…”