Color‐Stable Deep‐Blue Perovskite Light‐Emitting Diodes Based on Organotrichlorosilane Post‐Treatment

Abstract

Recent studies of sky‐blue perovskite light‐emitting diodes (PeLEDs) have extensively promoted optimal device design to achieve an external quantum efficiency (EQE) above 12%. However, the development of thin‐film deep‐blue PeLEDs lags dramatically behind, especially with regards to meeting the latest Rec. 2020 standard. A trichloro(3,3,3‐trifluoropropyl) silane post‐treatment that drives the emission of perovskite into the deep‐blue region, ranging from 440 to 460 nm, which meets the Rec. 2020 standard, is proposed. The chlorine ions released from the organotrichlorosilane molecules during their polycondensation reaction provide an addition halide source to fine tune the composition of the mixed halide perovskite films, leading to increase of bandgap and deep‐blue emission. In addition, hydrogen bonds between the hydroxy groups of silane molecules and halide anions in perovskite can suppress ion migration for improving emission stability. As a result, an optimal PeLED is developed with deep‐blue emission at 458 nm and excellent color stability, which yields an EQE and luminance of 1.1% and 130 cd m−2, respectively, representing a state‐of‐the‐art result for thin‐film PeLEDs in this emission region. This work paves the way to achieve high‐performance deep‐blue PeLEDs with stable emissions to meet the demand for potential applications such as full‐color display.

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

“…Furthermore, quasi-2D perovskites with mixed halides (e.g., L 2 A n−1 B n (Br x Cl 3−x ) 3n+1 and L 2 A n−1 B n (I x Br 3−x ) 3n+1 ) also exhibit shifted emission under continuous bias. [120,[176][177][178][179][180]…”

“…The anion-exchange process can also occur at the solid-liquid interface. [180,213] When CsPbBr 3 perovskite films were dipped into a mixed solution of chloroform (CF) and tributylphosphine (TBP) (Figure 10d), as shown in Equations ( 6)-( 8), TBP first detached the Cl − from CF, and then Cl − exchanged with Br − in the perovskite bulk. [213] By controlling the reaction time, the anion-exchange process can tune the emission wavelength from 520 to 470 nm.…”

Highly Efficient Pure‐Blue Perovskite Light‐Emitting Diode Leveraging CsPbBrxCl3−x/Cs4PbBrxCl6−x Nanocomposite Emissive Layer with Shallow Valence Band

“…To the best of our knowledge, this EQE is the highest value among all reported data for an emission of 470 nm or lower (Figure S12, Supporting Information). [26,28,[36][37][38][39][40][41][42] The operational stability of the PeLEDs fabricated under pristine and CsCl 0.2 m conditions was investigated (Figure 4e,f; and Figure S13, Supporting Information). The half-life time (T 50 ) of the PeLED fabricated under pristine and CsCl 0.2 m conditions was measured to be 510 and 595 s, respectively.…”

Biuret Induced Tin‐Anchoring and Crystallization‐Regulating for Efficient Lead‐Free Tin Halide Perovskite Light‐Emitting Diodes

“…Despite continual advancements in the luminous efficiency of lead (Pb) halide PeLEDs, [1][2][3][4] the perceived toxicity of Pb significantly inhibits their mass commercialization. The easy density and disturbing the structural rigidity; [31,32] Another reason is the fast crystallization that occurs during the solution process of Sn halide perovskite, resulting in a degraded perovskite morphology with limited coverage, enormous pinholes, and large grain boundaries.…”

“…Despite continual advancements in the luminous efficiency of lead (Pb) halide PeLEDs, [ 1–4 ] the perceived toxicity of Pb significantly inhibits their mass commercialization. The easy degradation of lead halide perovskites releases water‐soluble Pb salts, which can invade the human body and disturb neurological, nephritic, and endocrine systems.…”