Fusible Low Work Function Top Electrode for Vacuum-Free Perovskite Light-Emitting Diode Application: Role of OH-Terminated Sn Atoms at the Alloy Surface

Abstract

Hybrid organic−inorganic halide perovskite-based light-emitting diodes (PeLEDs) have attracted tremendous interest because of their higher external quantum efficiency and low production cost. Most of the high efficiency PeLEDs utilize a p−i−n structure geometry, which require a sufficiently low work function top metal electrodes for better charge injection. Also, PeLEDs can be fabricated at low temperature except the top metal electrodes. In conventional PeLEDs, metal electrodes are deposited by thermal deposition, which greatly reduces the production yield and enhances the complexity and production cost. Here, we have demonstrated a facile lowtemperature and vacuum-free deposition method for conformal coating of the low melting point alloy as the top cathode electrode which also facilitates efficient charge extraction. Ultraviolet photoelectron spectroscopy measurement has been performed to estimate the work function of this low melting point alloy. To our surprise, a sufficiently low work function (∼3.01 eV) has been observed despite all the constituents having a work function around 4.0 eV. XPS measurement confirms the presence of a metal hydroxide at the electrode interface which is responsible for achieving such a low work function due to surface polarization. These devices are relatively more stable compared to other low work function metal electrode-based PeLEDs.

Quantifying Capacitive and Diffusion-Controlled Charge Storage from 3D Bulk to 2D Layered Halide Perovskite-Based Porous Electrodes for Efficient Supercapacitor Applications

“…Hybrid halide perovskites (HHPs) are the materials of the decade as tremendous progress in perovskite solar cells, − perovskite light-emitting diodes, − perovskite-based detectors, and memristor applications has been observed owing to their superior optoelectronic properties such as high carrier mobility, , high absorption coefficient, , ambipolar charge transport, , high quantum yield, , high color purity, excellent defect tolerance with low-temperature solution −processing, and tunable emission over a broad spectrum . Due to the mixed electronic–ionic conductivity, hybrid perovskites have also attracted attention toward energy storage applications. − Ions in the perovskite materials (anions and cations) have much lower activation energies and modest ionic diffusion coefficients to move within the perovskite active layer when subjected to an external electric field or under light illumination. − This feature of HHPs is a merit for energy storage applications including many switchable photovoltaic and nonvolatile memory applications. , HHPs have been used in lithium-ion batteries (LIBs), photorechargeable batteries (PRBs), and supercapacitors. ,, Ahmad et al have demonstrated two-dimensional (2D) perovskite-based efficient PRBs having capacities of up to 100 mAh g –1 .…”

Electronic-Ionic Transport in MAPbBr3 Single Crystal: The Evidence of Super-Linear Power Law in AC Conductivity

“…Hybrid metal halide perovskites (MHPs) have attracted tremendous attention among the scientific community owing to their variegated applications in optoelectronic devices, such as solar cells, − light-emitting diodes (LEDs), − and memory devices . Apart from these, MHPs have recently attracted much attention as active layers for field-effect transistors (FETs), high-energy radiation detectors (X-ray and γ-ray), and imaging devices for medical diagnostics.…”

Characteristics of High-Power Impulse Magnetron Sputtering ITO/Ag/ITO Films for Application in Transparent Micro-LED Displays

“…To achieve balanced electron−hole transport and luminous efficiency in light-emitting diodes (LEDs), the cathode typically employs low work function metals as the electrodes in the stacked electrode. 3,4 Metal layers, such as Ca, Mg, Ag, and Al, are often employed as electrodes, 5 but the metal film can absorb excessive emission light and cannot effectively account for both high penetration and conductivity.…”