Highly Efficient Inherent Linearly Polarized Electroluminescence from Small‐Molecule Organic Single Crystals

Abstract

Small-molecule organic single crystals (SCs) with an inherent in-plane anisotropic nature enable direct linearly polarized light emission without the need for spatially separated polarizers and complex optical structures. However, the device performance is severely restricted by the starvation of appropriate SC emitters and the difficulty in the construction of efficient SC electroluminescence (EL) devices, leading to a low external quantum efficiency (EQE) of usually smaller than 1.5%. Here, highly efficient inherent linearly polarized light-emitting diodes (LP-LEDs) are demonstrated by exploiting 2,6-diphenylanthracene (DPA) SCs as intrinsically polarized emitters. The LP-LEDs exhibit a 2.5-fold enhanced maximum EQE of 3.38%, which approaches the theoretical limit for the DPA SC-based EL device and is the highest among organic SC-based LEDs reported thus far. More importantly, a high degree of polarization (DOP) up to 0.74 is achieved for the intrinsically polarized EL emission of the DPA SC-based LP-LEDs. By leveraging the highly efficient LP-LED, an interchip polarized optical communication system consisting of organic SCs is demonstrated for the first time. This work creates a solid foundation for the exploitation of a vast new library of small-molecule organic SCs for LP-LEDs and carries broad implications for polarized optics and relevant optoelectronic devices.

One-Dimensional CsCu2I3 Single-Crystal X-ray Detectors

“…Finally, the PL intensity of CsCu 2 I 3 SCs can still maintain 90% of the initial value, after being stored in air for 420 days (Figure i). These findings indicate that the CsCu 2 I 3 SCs have excellent stability, even surpassing that of lead-based perovskites. − …”

Novel solution-processed 2D organic semiconductor crystals for high-performance OFETs

“…27 For example, when MoS 2 changes from bulk material to monolayer, it will change from indirect band gap (band gap is 1.3 eV) to direct band gap (band gap is 1.9 eV), which causes monolayer MoS 2 to exhibit extremely strong fluorescent radiation in the visible light region. 28,29 Polarization optical responses induced by lattice anisotropy are observed in anisotropic 2D materials, [30][31][32] resulting in intense optical absorber research related to adjustable polarization, 33 wavelength, 34 and efficiency. 35 The ultrathin property of 2D materials and the negligible effect of thickness on carrier mobility make them among the most promising channel material candidates for diverse electronic applications, 36,37 including transistors, logical circuits, and neuromorphic electronics.…”

“…23,26,56,[60][61][62][63][64] Furthermore, 2DOSCs can act as clean and flat platforms for constructing heterojunctions and superlattices, which are helpful to achieve novel physics, diverse device structures, and versatile functions. 63,[65][66][67][68] Mono-/few layer 2DOSCs have excellent optical transparency and they have a dimension far smaller than the wavelength of light, which help achieve lower dark currents and noise, 55,69 and thus they are widely used in photodetectors, 55,70 organic light-emitting diodes (OLEDs), 71 and lasers, 72 as well as some special application scenarios such as polarized light detectors, 30,31 wide spectrum light detectors, 73 and neural network image sensors. 67,68 Compared with their bulk OSC counterparts, monolayer and fewmolecular-layer 2DOSCs can effectively reduce interlayer charge shielding and facilitate charge carrier injection and transport, which are of great significance for realizing electronic devices with better performance.…”

High-Efficiency Linearly Polarized Organic Light-Emitting Diodes

“…Another strategy involves introducing uniaxial oriented materials into the emissive layer. This includes the use of organic single crystals, , the self-aligned liquid crystal, , and conjugated polymers which are aligned through methods such as mechanical stretching, friction transfer, Langmuir−Blodgett deposition, and pre-aligned substrate . Nonetheless, this strategy often results in an even lower efficiency.…”