Silver-induced activation of 8-hydroxyquinolinato lithium as electron injection material in single-stack and tandem OLED devices

High voltage vacuum-processed perovskite solar cells with organic semiconducting interlayers

“…34,35 As for the case of BCP, the electron injection mechanism of Liq is not completely understood, but the most accepted hypothesis is that it is able to release metallic lithium upon reaction with the metallic cathode, leading to interfacial reduction of the underlying ETL. 36,37 In this work, we compared fully vacuum-deposited MAPI solar cells employing organic semiconductors as the transport and injection materials. We examined the inuence of different thin electron injection layers and of the metal work function on the performance of p-i-n solar cells, where the electron transport layer is deposited on top of the perovskite and before the metal electrode.…”

Enhanced Efficiency of Tandem Organic Light‐Emitting Diodes via Manipulating Heterojunction Composition of Charge Generation Unit

“…[ 1–3 ] Tandem OLEDs have been highlighted as a viable alternative because of their advantages over conventional OLEDs, such as high current efficiency and luminance at low current density, as well as long lifetime. [ 4–9 ] In a tandem OLED, two or more individual electroluminescent (EL) units are electrically connected in series via a connection unit, commonly called charge generation unit (CGU) or charge generation layer (CGL). The current efficiency of a tandem OLED containing N EL units ( N ≥ 2) should be N times that of a conventional OLED containing only a single EL unit.…”

“…As a matter of fact, the interfaces in the CGU control the inner charge generation and charge injection into the adjacent EL units. For these past years, many types of interfaces as CGUs in tandem OLEDs had been exploited, such as inorganics doped organic n–p junction, [ 10 ] ultrathin conductive metal layer combined with transition metal oxides, [ 7,11,12 ] and organic heterojunction (HJ). [ 9,13 ] CGUs incorporated with metals and inorganic materials have some disadvantages, high thermal evaporated temperature, unmatched deposition compatibility, and so on.…”

Optimizing Performance and Operational Stability of CsPbI3 Quantum-Dot-Based Light-Emitting Diodes by Interface Engineering

“…22 To overcome this issue, thin buffer layers (also often reported as electron injection layer, EIL) are employed with the metal electrode (bilayer cathode) to reduce the cathode work function. 23,24 Typical examples include inorganic alkali/ alkaline metal/compounds LiF/Al 10,12,23 or LiF/Au, 21 Cs 2 CO 3 /Al, 18,25 CsF/Al, 26 CaF/Al, 27 Ca/Al, 28 or Ca/Ag, 29 organic alkali/alkaline metal complex 8-quinolinolato lithium (Liq)/Al 24,30 or Liq/Ag, 31 8-quinolinolato sodium (Naq)/Al, 32 cesium quinoline-8-oxide (Csq)/Al, 33 and so on. Although the precise mechanism behind the enhanced electron injection of bilayer cathode is still unknown, plausible explanations are related with the metal-induced chemical reduction of the EIL and the subsequent doping of the ETL or by charge injection via quantum tunneling.…”

“…Another crucial but relatively underexplored aspect is to meliorate electron injection from cathodes into the ETL in standard stack LEDs (employing a HTL on a conducting substrate) and to balance it with the holes flowing through the device. , Typical metal electrodes such as aluminum (Al), silver (Ag), or gold (Au) are the most commonly used. ,, The high work function of Al, Ag, and Au makes electron injection in low-voltage electroluminescence devices arduous . To overcome this issue, thin buffer layers (also often reported as electron injection layer, EIL) are employed with the metal electrode (bilayer cathode) to reduce the cathode work function. , Typical examples include inorganic alkali/alkaline metal/compounds LiF/Al ,, or LiF/Au, Cs 2 CO 3 /Al, , CsF/Al, CaF/Al, Ca/Al, or Ca/Ag, organic alkali/alkaline metal complex 8-quinolinolato lithium (Liq)/Al , or Liq/Ag, 8-quinolinolato sodium (Naq)/Al, cesium quinoline-8-oxide (Csq)/Al, and so on. Although the precise mechanism behind the enhanced electron injection of bilayer cathode is still unknown, plausible explanations are related with the metal-induced chemical reduction of the EIL and the subsequent doping of the ETL or by charge injection via quantum tunneling. ,,− It is important to note that Liq is a metal–organic semiconductor and LiF is an insulator, and therefore, a small change in LiF thickness could severely affect the formation of a band-bending zone and restrict electron injection. − Therefore, an efficient LED operation also requires tuning of EILs/metal interfaces beside ETLs/emitter or HTLs/emitter interfaces.…”