Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. Despite ...recent advances in device efficiency, the stability of perovskite LEDs is still a major obstacle. Here, we demonstrate stable and bright perovskite LEDs with high energy conversion efficiencies by optimizing formamidinium lead iodide films. Our LEDs show an energy conversion efficiency of 10.7%, and an external quantum efficiency of 14.2% without outcoupling enhancement through controlling the concentration of the precursor solutions. The device shows low efficiency droop, i.e. 8.3% energy conversion efficiency and 14.0% external quantum efficiency at a current density of 300 mA cm
, making the device more efficient than state-of-the-art organic and quantum-dot LEDs at high current densities. Furthermore, the half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm
, comparable to the lifetime of near-infrared organic LEDs.
The retina, the most crucial unit of the human visual perception system, combines sensing with wavelength selectivity and signal preprocessing. Incorporating energy conversion into these superior ...neurobiological features to generate core visual signals directly from incoming light under various conditions is essential for artificial optoelectronic synapses to emulate biological processing in the real retina. Herein, self‐powered optoelectronic synapses that can selectively detect and preprocess the ultraviolet (UV) light are presented, which benefit from high‐quality organic asymmetric heterojunctions with ultrathin molecular semiconducting crystalline films, intrinsic heterogeneous interfaces, and typical photovoltaic properties. These devices exhibit diverse synaptic behaviors, such as excitatory postsynaptic current, paired‐pulse facilitation, and high‐pass filtering characteristics, which successfully reproduce the unique connectivity among sensory neurons. These zero‐power optical‐sensing synaptic operations further facilitate a demonstration of image sharpening. Additionally, the charge transfer at the heterojunction interface can be modulated by tuning the gate voltage to achieve multispectral sensing ranging from the UV to near‐infrared region. Therefore, this work sheds new light on more advanced retinomorphic visual systems in the post‐Moore era.
To approach an almost real retina perception, the first self‐powered optoelectronic synapses are designed that allow for selective detection of UV light from wide spectrum and real time preprocess UV signals without external batteries, which benefit from high‐quality organic asymmetric heterojunctions with flexible band structure engineering.
Solution‐processed, self‐organized multiple quantum well (MQW) perovskites possess good film coverage and high photoluminescence quantum efficiency, which are promising for high performance ...light‐emitting diodes (LEDs). However, due to the inclusion of insulating large organic cation as barrier layer, the charge transport in MQW perovskites is not as efficient as 3D perovskites, which limits the improvement of power conversion efficiency of MQW perovskite LEDs. Here, it is demonstrated that by molecular engineering, the conductivity of MQW perovskite film can be effectively increased by reducing the barrier width in QWs, thus leading to enhanced device performance. By controlling the constitution of the narrow‐barrier‐width MQW perovskites, one can achieve green LEDs with a high luminance of 30 000 cd m−2 at a low voltage of 6 V and a peak external quantum efficiency of 7.7%. Moreover, the green perovskite LEDs show a lifetime of 63 min with initial luminance of 1330 cd m−2, representing one of the best performing green perovskite LEDs. Here, a promising strategy is provided to further boost the efficiency, brightness, and stability of MQW perovskite LEDs.
The barrier width of multiple quantum well (MQW) perovskite is controlled through molecular engineering of the large organic cation. MQW perovskite films based on a novel benzimidazolium exhibit reduced barrier width and enhanced conductivity, leading to green perovskite light‐emitting diodes with high luminance and good stability.
Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. ...Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W
and luminance of over 37,000, 9,300, and 1,300 cd m
for sky blue, blue, and deep blue with Commission Internationale de l'Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.
3D perovskites are promising to achieve efficient and bright deep‐blue light‐emitting diodes (LEDs), which are required for lighting and display applications. However, the efficiency of deep‐blue 3D ...perovskite‐based LEDs is limited by high density of defects in perovskites, and their deep‐blue emission is not easy to achieve due to the halide phase separation and low solubility of chloride in precursor solutions. Here, an in situ halide exchange method is developed to achieve deep‐blue 3D perovskites by spin‐coating an organic halide salts solution to treat blue 3D perovskites. It is revealed that the halide‐exchange process is mainly determined by halide ion diffusion targeting a concentration equalization, which leads to homogeneous 3D mixed‐halide perovskites. By further introducing multifunctional organic ammonium halide salts into the exchange solution to passivate defects, high‐quality deep‐blue perovskites with reduced trap density can be obtained. This approach leads to efficient deep‐blue perovskite LEDs with a peak external quantum efficiency (EQE) of 4.6% and a luminance of 1680 cd m−2, which show color coordinates of (0.131, 0.055), very close to the Rec. 2020 blue standard. Moreover, the halide exchange method is bidirectional, and blue perovskite LEDs can be achieved with color coordinates of (0.095, 0.160), exhibiting a high EQE of 11.3%.
Efficient deep‐blue perovskite light‐emitting diodes (LEDs) are achieved by introducing multifunctional organic halide salts to treat perovskite films, which can facilitate halide exchange and passivate defects of 3D perovskites. The LEDs exhibit a peak external quantum efficiency of 4.6% and a luminance of ≈1680 cd m−2, which show color coordinates of (0.131, 0.055), close to the Rec. 2020 blue standard.
Efficient and stable deep-blue emission from perovskite light-emitting diodes (LEDs) is required for their application in lighting and displays. However, this is difficult to achieve due to the phase ...segregation issue of mixed halide perovskites and the challenge of synthesizing high-quality single-halide deep-blue perovskite nanocrystals through a traditional method. Here, we show that an antisolvent treatment can facilitate the in situ formation of perovskite nanocrystals using a facile spin-coating method. We find that the dropping time of the antisolvent can significantly affect the constitution of nanocrystal perovskite films. With a delay in the start time of the antisolvent treatment, small single-halide perovskite nanocrystals can be achieved, exhibiting efficient deep-blue emission. The LED device shows a stable electroluminescence (EL) peak at 465 nm, with a peak external quantum efficiency and a peak current efficiency of 2.4% and 2.5 cd A–1, respectively. This work provides a facile approach to changing the size of perovskite nanocrystals, thus effectively tuning their EL emission spectra.
tRNA-derived small RNAs (tsRNAs, or tRFs) are a new category of regulatory noncoding RNAs with versatile functions. Recent emerging studies have begun to unveil distinct features of tsRNAs based on ...their sequence, RNA modifications, and structures that differentially impact their functions towards regulating multiple aspects of translational control and ribosome biogenesis.
The discovery of RNAs (for example, messenger RNAs, non-coding RNAs) in sperm has opened the possibility that sperm may function by delivering additional paternal information aside from solely ...providing the DNA
. Increasing evidence now suggests that sperm small non-coding RNAs (sncRNAs) can mediate intergenerational transmission of paternally acquired phenotypes, including mental stress
and metabolic disorders
. How sperm sncRNAs encode paternal information remains unclear, but the mechanism may involve RNA modifications. Here we show that deletion of a mouse tRNA methyltransferase, DNMT2, abolished sperm sncRNA-mediated transmission of high-fat-diet-induced metabolic disorders to offspring. Dnmt2 deletion prevented the elevation of RNA modifications (m
C, m
G) in sperm 30-40 nt RNA fractions that are induced by a high-fat diet. Also, Dnmt2 deletion altered the sperm small RNA expression profile, including levels of tRNA-derived small RNAs and rRNA-derived small RNAs, which might be essential in composing a sperm RNA 'coding signature' that is needed for paternal epigenetic memory. Finally, we show that Dnmt2-mediated m
C contributes to the secondary structure and biological properties of sncRNAs, implicating sperm RNA modifications as an additional layer of paternal hereditary information.
Although high-throughput RNA sequencing (RNA-seq) has greatly advanced small non-coding RNA (sncRNA) discovery, the currently widely used complementary DNA library construction protocol generates ...biased sequencing results. This is partially due to RNA modifications that interfere with adapter ligation and reverse transcription processes, which prevent the detection of sncRNAs bearing these modifications. Here, we present PANDORA-seq (panoramic RNA display by overcoming RNA modification aborted sequencing), employing a combinatorial enzymatic treatment to remove key RNA modifications that block adapter ligation and reverse transcription. PANDORA-seq identified abundant modified sncRNAs-mostly transfer RNA-derived small RNAs (tsRNAs) and ribosomal RNA-derived small RNAs (rsRNAs)-that were previously undetected, exhibiting tissue-specific expression across mouse brain, liver, spleen and sperm, as well as cell-specific expression across embryonic stem cells (ESCs) and HeLa cells. Using PANDORA-seq, we revealed unprecedented landscapes of microRNA, tsRNA and rsRNA dynamics during the generation of induced pluripotent stem cells. Importantly, tsRNAs and rsRNAs that are downregulated during somatic cell reprogramming impact cellular translation in ESCs, suggesting a role in lineage differentiation.
Adaptation to high-altitude hypobaric hypoxia has been shown to require a set of physiological traits enabled by an associated set of genetic modifications, as well as transcriptome regulation. These ...lead to both lifetime adaptation of individuals to hypoxia at high altitudes and generational evolution of populations as seen for instance in those of Tibet. Additionally, RNA modifications, which are sensitive to environmental exposure, have been shown to play pivotal biological roles in maintaining the physiological functions of organs. However, the dynamic RNA modification landscape and related molecular mechanisms in mouse tissues under hypobaric hypoxia exposure remain to be fully understood. Here, we explore the tissue-specific distribution pattern of multiple RNA modifications across mouse tissues.
By applying an LC-MS/MS-dependent RNA modification detection platform, we identified the distribution of multiple RNA modifications in total RNA, tRNA-enriched fragments, and 17-50-nt sncRNAs across mouse tissues; these patterns were associated with the expression levels of RNA modification modifiers in different tissues. Moreover, the tissue-specific abundance of RNA modifications was sensitively altered across different RNA groups in a simulated high-altitude (over 5500 m) hypobaric hypoxia mouse model with the activation of the hypoxia response in mouse peripheral blood and multiple tissues. RNase digestion experiments revealed that the alteration of RNA modification abundance under hypoxia exposure impacted the molecular stability of tissue total tRNA-enriched fragments and isolated individual tRNAs, such as tRNA
, tRNA
, tRNA
, and tRNA
. In vitro transfection experiments showed that the transfection of testis total tRNA-enriched fragments from the hypoxia group into GC-2spd cells attenuated the cell proliferation rate and led to a reduction in overall nascent protein synthesis in cells.
Our results reveal that the abundance of RNA modifications for different classes of RNAs under physiological conditions is tissue-specific and responds to hypobaric hypoxia exposure in a tissue-specific manner. Mechanistically, the dysregulation of tRNA modifications under hypobaric hypoxia attenuated the cell proliferation rate, facilitated the sensitivity of tRNA to RNases, and led to a reduction in overall nascent protein synthesis, suggesting an active role of tRNA epitranscriptome alteration in the adaptive response to environmental hypoxia exposure.
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