Bright Perovskite Nanocrystal Films for Efficient Light-Emitting Devices

Abstract

The high photoluminescence efficiency, high color purity, and easy tunable bandgap make inorganic perovskite nanocrystals very attractive in luminescent display applications. Here, we report a color-saturated, red light-emitting diode (LED) using an inverted organic/inorganic hybrid structure and perovskite nanocrystals. We demonstrated that through a simple post treatment to the perovskite nanocrystals with polyethylenimine, the surface defects of the perovskite nanocrystals could be well passivated, leading to great enhancements on their absolute photoluminescence quantum yield and photoluminescence lifetime. Through using a well-passivated perovskite nanocrystal film and optimizing the charge balance, we achieved an electroluminescence LED with a current efficiency of 3.4 cd A, corresponding to an external quantum efficiency (EQE) of 6.3%, which is the highest value reported among perovskite NC LEDs so far.

Surface ligand modification of cesium lead bromide nanocrystals for improved light-emitting performance

“…4a and b, with a cross-section scanning electron microscopy (SEM) image shown in Fig. S5.† Following our previous work, 16 the device consists of multiple layers: indium tin oxide (ITO, cathode), ZnO NC layer (electron transport layer, ETL, 40 nm thickness), CsPbBr 3 NCs (20 nm thickness), 4,4′-bis(carbazole-9-yl)biphenyl and 4,4′,4″-tris(carbazol-9-yl)triphenylamine organic molecules (hole transport layer, HTL, 50 nm thickness), and MoO x /Au (anode). With the exception of HTL and MoO x /Au layers being deposited by thermal vacuum deposition, ZnO and perovskite NC layers were sequentially spin-coated from their corresponding solutions.…”

“…1 These NCs exhibit a high photoluminescence (PL) quantum yield (QY) of nearly 100%, 2–4 a narrow emission line-width and a wide color gamut. They are widely applied in solar cells, 5–9 LEDs 10–16 and lasing. 17,18 However, compared to the traditional cadmium chalcogenide quantum dots, 19–21 CsPbX 3 NCs showed poor colloidal stability during purification procedures and storage.…”

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…[42]). Apparently, the aforementioned superior optical www.advmat.de www.advancedsciencenews.com merits provide solid foundation for optoelectronic applications in light harvester, [43][44][45][46] LEDs, [33,34,[47][48][49][50][51][52][53][54][55][56] high-definition displays, [33,48] low-threshold lasers, [40,[57][58][59][60] and photodetectors. [33] In spite of the superiority to metal chalcogenide QDs, the main shortcoming of all-inorganic perovskite NCs is the degradation under service environment (see details in section 5).…”

Spontaneous Silver Doping and Surface Passivation of CsPbI3 Perovskite Active Layer Enable Light-Emitting Devices with an External Quantum Efficiency of 11.2%

“…The wide bandgap ZnO NC film was chosen as ETL and at the same time served as a holeblocking layer (HBL) because of its high electron mobility, excellent optical transparency, and the deep-lying VBM (valence band maximum, −7.2 eV). 19 The TCTA film was chosen as HTL and at the same time served as an electron-blocking layer (EBL) because of its suitable highest occupied molecular orbital (HOMO, −5.7 eV) and low electron affinity (−2.3 eV). 20 The combination of ZnO HBL and TCTA EBL sandwiched around the CsPbI 3 NC emitting layer allowed for confinement of injected charge carriers resulting in an efficient radiative recombination.…”

“…The PEI interlayer not only lowered the work function of cathode contacts but also helped to maintain charge neutrality of CsPbI 3 NC emitters and preserve their superior emissive properties. 19 …”