Aggregation‐induced emission (AIE) is a beneficial strategy for generating highly effective solid‐state molecular luminescence without suffering losses in quantum yield. However, the majority of reported AIE‐active molecules exhibit only strong fluorescence, which is not ideal for electrical excitation in organic light‐emitting diodes (OLEDs). By introducing various substituent groups onto the biscarbazole compound, a series of molecular materials with aggregation‐induced phosphorescence (AIP) is designed, which exhibits two distinctly different phosphorescence bands and an absolute solid‐state room‐temperature phosphorescence quantum yield up to 64%. Taking advantage of the AIE feature, the AIP molecules are fabricated into OLEDs as a homogeneous light‐emitting layer, which allows for relatively small efficiency roll‐off and shows an external electroluminescence quantum yield of up to 5.8%, more than the theoretical limit for purely fluorescent OLED devices. The design showcases a promising strategy for the production of cost‐effective and highly efficient OLED technology.

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Aggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient room temperature phosphorescence (RTP) in bulk by restricting molecular motions. Here, we show that by utilizing triphenylamine (TPA) as an electronic donor that connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Distinct dual phosphorescence bands emitting from largely localized donor and acceptor triplet emitting states could be recorded at lowered temperatures; at room temperature, only a merged RTP band is present. Theoretical investigations reveal that the two temperature-dependent phosphorescence bands both originate from local/global minima from the lowest triplet excited state (T1). The reported molecular construct serves as an intermediary case between a fully conjugated donor-acceptor system and a donor/acceptor binary mix, which may provide important clues on the design and control of high-freedom molecular systems with complex excited-state dynamics.

This article reports a nonpolar GaN metal−semiconductor− metal (MSM) photodetector (PD) with an ultrahigh responsivity and an ultrafast response speed in the ultraviolet spectral region, which was fabricated on nonpolar (112̅ 0) GaN stripe arrays with a major improvement in crystal quality grown on patterned (110) silicon substrates by means of using our twostep processes. Our nonpolar GaN MSM-PD exhibits a responsivity of 695.3 A/W at 1 V bias and 12628.3 A/W at 5 V bias, both under 360 nm ultraviolet illumination, which are more than 20 times higher and 4 orders of magnitude higher compared to the current state-of-the-art photodetector, respectively. The nonpolar GaN MSM-PD displays a rise time and a fall time of 66 and 43 μs, respectively, which are 3 orders of magnitude faster compared to the current state-of-the-art photodetector.

Room-temperature phosphorescence (RTP) originating from higher-lying triplet excitons remains a rather rarely documented occurrence for purely organic molecular systems. Here, we report two naphthalenebased RTP luminophores whose phosphorescence emission is enabled by radiative decay of high-lying triplet excitons. In contrast, upon cooling the dominant phosphorescence originates from the lowest-lying triplet excited state, which is manifested by a red-shifted emission. Photophysical and theoretical studies reveal that the unusual RTP results from thermally activated excitonic coupling between different conformations of the compounds. Aggregation-regulated excitonic coupling is observed when increasing the doping concentration of the emitters in poly(methylmethacrylate) (PMMA). Further, the RTP quantum efficiency improves more than 80-fold in 1,3-bis(N-carbazolyl)benzene (mCP) compared to that in PMMA. This design principle offers important insight into triplet excited state dynamics and has been exploited in afterglowindicating temperature sensing.

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2D materials and their van der Waals heterostructures are of great fundamental interest and have potential applications in emerging electronics devices. However, atomically thin photodetector applications have suffered from performance limitations because of low optical absorption. Here, a near-infrared photodetector based on methylammonium lead halide perovskite quantum dots (MQDs), combined with Ta 2 NiSe 5 van der Waals heterostructures, is fabricated to take advantage of their energy band alignment. An ultrasensitive photoresponse with a detectivity of 6.0 × 10 12 Jones for 800 nm illumination is demonstrated. Furthermore, the field-effect mobility and responsivity are enhanced by factors of 2 and 7.4, respectively, by interfacing Ta 2 NiSe 5 and the MQDs. These results indicate that the optoelectrical properties of 2D ternary Ta 2 NiSe 5 can be significantly optimized via hybridization with MQDs and can accelerate the evolution of MQD-van der Waals heterostructure-based devices.

Dual-phosphorescence emission can be realized via chemical conjugation between an n–π* type of luminophore and a π–π* one.