Efficient Perovskite Light‐Emitting Diodes with a Siloxane‐Blended Organic Hole Transport Layer

Abstract

Metal halide perovskite light‐emitting diodes (LEDs) are promising for future display applications because of their excellent advantages, such as high external quantum efficiency, emission color tunability, and high emission color purity. Although solution processing widely used for perovskite film fabrication is an additional advantage, there are cases in which fabricating a perovskite‐emitting layer with spin‐coating results in the dissolution of an underlying organic hole transport layer (HTL). As a result, since a perovskite layer comes into partial contact with an indium tin oxide (ITO) anode layer, excited states formed in a perovskite‐emitting layer are quenched by charge transfer to ITO. In this study, it is shown that adding tetraethyl orthosilicate (TEOS) into a HTL material of poly(N‐vinylcarbazole) (PVCz) is an effective method used to overcome this issue. Upon heating, the hydrolysis reaction of TEOS molecules takes place in PVCz films to form a siloxane network, which makes PVCz films insoluble and, therefore, alleviates the excited‐state quenching. It is demonstrated that using the siloxane‐blended PVCz HTL increases external quantum efficiencies of perovskite LEDs to 15.4 ± 0.3% from the original 10.4 ± 0.3% by about 1.5 times.

Advancements in Interfacial Engineering for Perovskite Light‐Emitting Diodes

“…introduced a cross linkable polymer additive, tetraethyl orthosilicate (TEOS), into the conventional poly(N‐vinylcarbazole) (PVK) HTL. Upon heating after the spin coating process, these blended polymers can form a silicon oxide polymer (siloxane), rendering the film insoluble in common polar solvents, as depicted in Figure 6c–e [16c] . The resulting device exhibited a 1.5‐fold increase in EQE compared to the unmodified counterpart, attributed to a less damaged HTL layer during the perovskite deposition process, reducing the quenching effect.…”

“…(e) schematics of siloxane network formation within PVCz HTL. Reproduced with permission [16c] . © 2022 The Authors.…”

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

“…The introduced alkoxysilane converts into silicon oxides with insulating properties from a wide bandgap, good thermal stability, high light transmittance, and good chemical stability toward perovskites, and therefore have been applied to various optoelectronic devices. [26][27][28] Recently, Matsushima et al fabricated a siloxane network to form an insoluble poly(N-vinyl carbazole) (PVCz) hole transporting layer by incorporating tetraethyl orthosilicate (TEOS) to PVCz and demonstrated 15.4% of EQE max from a normal PeLEDs owing to the suppressed quenching of excited charges. [28] Here in this study, we modulate the band energy level of the SnO 2 -based EIL by controlling the TEOS concentration of the alkoxysilane-treated SnO 2 interlayer.…”

“…[26][27][28] Recently, Matsushima et al fabricated a siloxane network to form an insoluble poly(N-vinyl carbazole) (PVCz) hole transporting layer by incorporating tetraethyl orthosilicate (TEOS) to PVCz and demonstrated 15.4% of EQE max from a normal PeLEDs owing to the suppressed quenching of excited charges. [28] Here in this study, we modulate the band energy level of the SnO 2 -based EIL by controlling the TEOS concentration of the alkoxysilane-treated SnO 2 interlayer. The incorporated TEOS in SnO 2 colloidal solution converts into silicon oxide (siloxane) by the sol-gel reaction.…”

“…fabricated a siloxane network to form an insoluble poly(N‐vinyl carbazole) (PVCz) hole transporting layer by incorporating tetraethyl orthosilicate (TEOS) to PVCz and demonstrated 15.4% of EQE max from a normal PeLEDs owing to the suppressed quenching of excited charges. [ 28 ]…”