Color Conversion Research Articles

Synthesis of SiO2-coated perovskite quantum dots for micro-LED display applications

Cadmium quantum dots (QDs) have good luminous properties, but cadmium is toxic. So, cadmium-free perovskite QDs were synthesized by chemical solution methods, realizing the new structure of the green CsPbBr3/Cs4PbBr6 perovskite QDs. The SiO2 layer passivated the perovskite QDs by the sol-gel method and hydrolysis of tetramethoxysilane (TMOS) and then dispersed in a polar solvent to facilitate mixing with negative photoresist (SU8-3010) to ensure their luminous properties are not affected by moisture and oxygen. Afterward, perovskite QDs were exposed and developed on the glass substrate by a photolithography process. The pixels were spaced apart through the black matrix to reduce the crosstalk between each other. Applying the pixelated perovskite QDs to the blue light micro-light-emitting diodes (LED) display as the color conversion layer showed that excessive blue light could penetrate through the green pixels, decreasing color purity. Therefore, we used a 23-layer distributed Bragg reflector (DBR) to reflect excess blue light on pixels back to perovskite QDs. DBR did not filter the green light, and the actual luminous intensity of green light increased by 118%, and the transmittance of blue light was only 0.5%. Finally, the alignment attaching of the graph pixelated perovskite QDs on a glass substrate to the blue light display realized monochrome/area color and full-color micro-LED display.

Polyvinyl Butyral Polymeric Host Material-Based Fluorescent Thin Films to Achieve Highly Efficient Red and Green Colour Conversion for Advanced Next-Generation Displays.

Rare-earth element-free fluorescent materials are eco-friendlier than other traditional fluorescent precursors, such as quantum dots and phosphors. In this study, we explore a simple and facile solution-based technique to prepare fluorescent films, which are highly stable under ordinary room conditions and show hydrophobic behaviour. The proposed hybrid material was designed with hybrid composites that use polyvinyl butyral (PVB) as a host doped with organic dyes. The red and green fluorescent films exhibited quantum yields of 89% and 80%, respectively, and both are very uniform in thickness and water resistant. Additionally, PVB was further compared with another polymeric host, such as polyvinylpyrrolidone (PVP), to evaluate their binding ability and encapsulation behaviour. Next, the effect of PVB on the optical and chemical properties of the fluorescent materials was studied using UV spectroscopy and Fourier transform infrared spectroscopy. The analysis revealed that no new bond was formed between the host material and fluorescent precursor during the process, with intermolecular forces being present between different molecules. Moreover, the thickness of the fluorescent film and quantum yield relation were evaluated. Finally, the hydrophobic nature, strong binding ability, and optical enhancement by PVB provide a powerful tool for fabricating a highly efficient fluorescent film with enhanced stability in an external environment based on its promising encapsulation properties. These efficient fluorescent films have a bright potential in colour conversion for next-generation display applications.

Pure Green Upconversion from a Multicolor Downshifting Perovskite Crystal

AbstractLanthanide‐doped halide perovskite has emerged as a promising phosphor for multimode luminescence. Here, a chloride‐based perovskite single crystal is reported, namely Cs2NaInCl6:Yb3+,Er3+, that is grown in a hydrothermal reactor. The as‐grown crystals feature two distinct luminescence behaviors under UV and 980 nm laser excitation, respectively. Under UV lamp excitation, the crystal shows a multicolor emission of sharp bands at 448, 550, and 660 nm, covering a wide color gamut in CIE diagram. In stark contrast, the crystal under 980 nm excitation exhibits a pure green upconversion with a green‐to‐red ratio up to 211. The universal green dominance is further demonstrated in many chlorides, including Cs2AgInCl6, Cs2NaBiCl6, and Cs2AgBiCl6. The strong green upconversion is used for optical thermometry, which demonstrates an unprecedented sensitivity up to 9.3% K−1 at the low temperature end. The work introduces a kind of new hosts for single‐band upconversion luminescence, opening up many possibilities in areas such as low‐threshold laser and pure‐green color converter.

Vigorous high-efficiency YAGG:Ce phosphor-in-glass film for next-generation laser lighting applications

It is an important challenge to select suitable color converters and apply them to laser diodes (LDs) lighting field. Sapphire plates are used as substrates for phosphor-in-glass films (PiFs) due to their ultrahigh thermal conductivity (∼ 30 W m−1 K−1). Herein, Y3Al3.5Ga1.5O12:Ce3+ (YAGG:Ce) phosphor mixing silicate glass powder is successfully sintered on sapphire plates to fabricate YAGG:Ce phosphor-in-glass film (PiF). The microstructure appearance and photoelectric characteristics of the efficient green color converter are studied in detail. In addition, it is worth noting that the maximum internal quantum efficiency of the prepared PiF is 92%, which is close to that of the original phosphor (98%). Meanwhile, the saturation threshold of YAGG:Ce PiF reaches 38.96 W/mm2 with luminous efficiency (LE) of 230.85 lm/W under the excitation of 460 nm blue LD. Notably, PiF has ultra-high power density while still maintaining such high LE. In order to highlight the application of this color converter in laser lighting, we assemble laser flashlights and fireflies lights. The test of the laser flashlight shows excellent performances such as high brightness, strong focusing effect and wide irradiation range. All indications manifest that YAGG:Ce PiF is an excellent green color converter.

Polymer‐Encapsulated Halide Perovskite Color Converters to Overcome Blue Overshoot and Cyan Gap of White Light‐Emitting Diodes

AbstractCurrently, the most popular way to manufacture white light‐emitting diodes (WLEDs) is based on blue‐emitting InGaN LED chips (440–460 nm) and yellow‐emitting phosphor coating (520–700 nm) to produce white light lighting. However, because conventional white WLEDs lack the uniformly distributed continuous emission spectrum compared to natural sunlight: “blue overshoot” (extra 440–460 nm blue‐light can cause damage to the retina) and “cyan gap” (470–520 nm wavelength range). Here, a novel strategy to “kill two birds with one stone” is reported: using the stable and bright polymer encapsulated perovskite nanocrystals (PNCs) composite films as the cyan color converters that efficiently absorb the “blue overshoot” and effectively emit the cyan light to fill the “cyan gap”. A series of polymer‐encapsulated PNC films is achieved that can reach very high photoluminescence quantum yield (PL QY) of 90–95% under 450 nm blue‐light excitation. Importantly, both 370 nm UV‐excited WLED and 455 nm blue‐excited WLED devices are constructed that exhibit smoothly and evenly distributed white light without blue overshoot and cyan gap, which was not achieved before for blue‐excited cyan‐emissive materials. This study paves the way toward the application of PNC color converters in the next generation full‐visible‐spectrum WLED lighting that mimic the natural daylight.

Photoluminescence Behaviors in Self-Assembly Supramolecular Pyridinium Salts

The host–guest supramolecular organic salts would be of great interest due to their excellent optical and electronic properties. Herein, we report three supramolecular materials, o-2MAP, m-3MAP, and p-4MAP, composed of 18-crown-6 and pyridine amine salts, which are crystallized in space groups P1̅, P1̅, and P21/n with a pendulum-like structural variation at room temperature. They all show blue photoluminescence with photoluminescence quantum yields (PLQYs) of 26.85, 77.08, and 32.67%, respectively. The experimental and theoretical analyses reveal that PL emission is associated with strong π–π * and n–π* absorption and charge transition, while hydrogen bond nonvalent interactions affect their structures and cause the enhancement of PLQY. Especially, deep-blue PL materials m-3MAP with the highest PLQY have been used as excellent color conversion media to fabricate ultraviolet light-emitting diodes (UV-LEDs) and anticounterfeiting inks for handwriting and transfer-printing. This work caters to a reliable strategy to design novel optical supramolecular materials and extends their applications for PL materials.

Effect of radiative and nonradiative energy transfer processes of light-emitting diodes combined with quantum dots for visible light communication

Though light-emitting diodes (LEDs) combined with various color conversion techniques have been widely explored for VLC (visible light communication), E-O (electro-optical) frequency responses of devices with quantum dots (QDs) embedded within the nanoholes have rarely been addressed. Here we propose LEDs with embedded photonic crystal (PhC) nanohole patterns and green light QDs for studying small-signal E-O frequency bandwidths and large signal on–off keying E-O responses. We observe that the E-O modulation quality of PhC LEDs with QDs is better than a conventional LED with QDs when the overall blue mixed with green light output signal is considered. However, the optical response of only QD converted green light shows a contradictory result. The slower E-O conversion response is attributed to multi-path green light generation from both radiative and nonradiative energy transfer processes for QDs coated on the PhC LEDs.

Enhanced Color Conversion of Quantum Dots Located in the Hot Spot of Surface Plasmon Coupling

For improving the performance of the photon color conversion from the energy of an InGaN/GaN quantum-well (QW) structure into the longer-wavelength emission of a colloidal quantum dot (QD), we insert the photoresist solution of the QD into a surface nano-hole, whose bottom face is about 10 nm higher than the top QW. The sample top surface is then cleaned for depositing Ag nanoparticles (NPs) to induce the surface plasmon (SP) coupling with the QW structure such that the QDs inside the nano-holes are located in the region of strong field distribution (hot spot). In this situation, the SP coupling can enhance the Förster resonance energy transfer (FRET) from QW into QD and the QD emission efficiency for producing a stronger color conversion process. The nanoscale-cavity effect of the nano-hole structure can further strengthen the SP-coupling enhanced FRET and QD emission.

Ultrahigh Color Conversion Efficiency Nano-Light-Emitting Diode With Single Electrical Contact

Realizing full color GaN-based micro- and nano-light-emitting diode (nLED) displays with quantum dots (QDs) being the color conversion media remains challenging because of the limited QD color conversion efficiency (CCE). In this article, by using GaN-based nanorod LED as the light source and exciting the QDs by nonradiative energy transfer (NRET) method, a nanorod LED with ultrahigh CCE has been realized. At the same time, a single electrical contact alternating current (ac)-driven electroluminescence (EL) method is adopted to investigate the relationship between frequency and nLED performance. Different from the double terminal injection mode, on the premise of lighting up the nanorod LED, the ac-driven can also avoid the necessity of external p-type and n-type electrodes, thus simplified the manufacturing process of LED. The final optical measurement shows that the CCE of this hybrid color conversion nLED driven by single contact electrode can reach up to 86.67% under the ac voltage of 60 V and an ac frequency of 14.2 MHz, which shows that the energy utilization efficiency can be effectively improved by NRET.

Abstract P4-03-41: Prospective observational study of breast cancer patients during the cycle of chemotherapy with taxanes: evaluation of the incidence and prevalence of peripheral neuropathy

Abstract OBJECTIVE: To evaluate the prevalence of sensitivity changes in patients during the cycle of chemotherapy with taxanes and the impacts on quality of life. DESIGN: A prospective, observational, Approved study was conducted at the Oncomastology outpatient clinic of Hospital São Paulo- Unifesp, in the period from November 2018 to February 2022, where 102 women with breast cancer were selected and 79 patients who underwent chemotherapy with paclitaxel were included. METHODS: Collection of demographic and clinical information. Used stesiometer that assessed sensitivity in dermatos and myotomes in the following body regions: arms, hands, legs and feet. FACT/GOG-Ntx Questionnaire analyzed the quality of life and chemotherapy-induced peripheral neuropathy of the patients before starting chemotherapy. All participants were informed and signed an informed consent form. RESULTS: The mean age was 49 years, mean BMI was 27.95Kg/m2, NICC (Invasive Carcinoma not special) represented 89.9% of the sample, 88.6% had Neoadjuvant Chemotherapy, regarding the size of the tumor 45.6% presented from 2 to 5 cm, of the pre existing diseases Diabetes mellitus 15.2% and Systemic Arterial Hypertension 30.4%. The initial moment in relation to sensitivity alterations, of the arm regions presented (right C6 (HC 1.05-1.23) left C6 (HC 1.05- 1.23), and legs (right L5 (HC 1.14 -1.55) left L5 (HC1.22 - 1.52) and right S1 (HC 1.21-1.47) left S1 (HC 1.21-1.48). The conversion of the Estesiometer colors into numbers followed as follows, Green (1.0): normal sensitivity, Blue (2.0): decreased sensitivity. The FACT/Taxane (TOI) quality of life Questionnaire (30 items) its scores 0-120,(average 91.44 points) demonstrates in its response impairment in more than 80 % in the quality of life in the domains. Physical Well-Being-PWB (0-28 points) (mean 20.28/HC 18.88-21.66), Functional Well-Being-FWB (0-28 points) (mean16.00/HC14.22-17.22) and in the specific questions about chemotherapy-induced peripheral neuropathy (CPIN), TaxS (0-64 points) (mean 55.16/HC 52.74-57.26) reduced scores. CONCLUSION: It is concluded that mean age, overweight, tumors between 02 and 05 cm were the most prevalent among patients diagnosed with breast cancer. At the beginning of chemotherapy containing paclitaxel, sensitivity changes were not present characterizing arthralgia, myalgia and the hand-foot syndrome (CPIN). The quality of life evaluated by FACIT/Taxane, showed a reduction of 80% in the scores of the domains Physical Well-Being-PWB, Functional Well-Being-FWB and general quality of life, that is, the quality of life of patients from the time of diagnosis is already very compromised. Key words: Breast neoplasm, adjuvant drug treatment, chemotherapy, quality of life. Number of Opinion: 2.351.174 DATA OF THE OPINION, CEP Number: 0934/2017 of the ethics in research committee. Registered in Clinical Trials on 12/12/2017, protocol number -NCT 03373032. Table 1: Results of the sensitivity of dermatos and myths (monofilaments) undergoing chemotherapy cycles with paclitaxel (eyes closed) Legend: Analysis of quantitative frequencies, Mean, Standard Deviation and Confidence Interval, Percentage (%) and Absolute number. Citation Format: Roberta P. Costa Luz, Carmen S. Alliz, Samantha K. Lopes de Almeida Rizzi, Cinira Haddad, Christiano Bittencourt Machado, Afonso Nazário, Gil Facina. Prospective observational study of breast cancer patients during the cycle of chemotherapy with taxanes: evaluation of the incidence and prevalence of peripheral neuropathy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-41.

Performance optimization of Ce:YAG sapphire films for high power density white laser-driven lighting applications

To withstand higher power density (PD), exhibit higher luminous efficiency (LE), use in smaller size and lower cost has become the direction of solid-state lighting technology. In the face of high-density laser irradiation and strong thermal shock, improving the performance of color conversion materials related to laser illumination has become a research hotspot. In this study, The Y3Al5O12:Ce3+ phosphor-in-glass film (Ce:YAG-PiF) was obtained by scraping method. The optimized Ce: YAG-PiF external quantum efficiency (EQE) reaches 74.7%, closing to the phosphor (EQE = 78.47%). Excitingly, at 573 K, the thermal conductivity of sample remains at 9.47 W m−1 K−1. Besides, the sample has an ultra-high LE of 256 lm/W @ 32.47 W/mm2. After recombining with the red phosphor CaAlSiN3:Eu2+ (CASN), the color rendering index (CRI) is 84.6, the correlation color temperature (CCT) is 5594 K, and the LE is 192.91 lm/W @ 39.87 W/mm2. More importantly, the relative intensity of laser module packaged by Ce:YAG & CASN-PiF decreased by 15% when tested at 4 W for 24 h. Besides, the packaged laser flashlight has good collimation within a visible illuminance. All the results show that the prepared sample can maintain high emission intensity at high laser PD and have a good heat resistance, which is a promising color conversion material in the field of solid-state laser illumination.

Colorimetric characterization of the wide-color-gamut camera using the multilayer artificial neural network.

In order to realize colorimetric characterization for the wide-color-gamut camera, we propose using the multilayer artificial neural network (ML-ANN) with the error-backpropagation algorithm, to model the color conversion from the RGB space of camera to theX Y Z space of the CIEXYZ standard. In this paper, the architecture model, forward-calculation model, error-backpropagation model, and the training policy of the ML-ANN were introduced. Based on the spectral reflectance curves of the ColorChecker-SG blocks and the spectral sensitivity functions of the RGB channels of typical color cameras, the method of producing the wide-color-gamut samples for the training and testing of the ML-ANN was proposed. Meanwhile, the comparative experiment employing different polynomial transforms with the least-square method was conducted. The experimental results have shown that, with the increase of the hidden layers and the neurons in each hidden layer, the training and testing errors can be decreased obviously. The mean training errors and mean testing errors of the ML-ANN with optimal hidden layers have been decreased to 0.69 and 0.84 (color difference of CIELAB), respectively, which is much better than all the polynomial transforms, including quartic polynomial transform.

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

Colloidal CdSe/ZnS quantum dots (QD) enhanced micro-LEDs with sizes varying from 10 to 100 μm were fabricated and measured. The direct photolithography of quantum-dot-contained photoresists can place this color conversion layer on the top of an InGaN-based micro-LED and have a high throughput and semiconductor-grade precision. Both the uncoated and coated devices were characterized, and we determined that much higher brightness of a QD-enhanced micro-LED under the same current level was observed when compared to its AlGaInP counterpart. The color stability across the device sizes and injection currents were also examined. QD LEDs show low redshift of emission wavelength, which was recorded within 1 nm in some devices, with increasing current density from 1 to 300 A/cm2. On the other hand, the light conversion efficiency (LCE) of QD-enhanced micro-LEDs was detected to decrease under the high current density or when the device is small. The angular intensities of QD-enhanced micro-LEDs were measured and compared with blue devices. With the help of the black matrix and omnidirectional light emission of colloidal QD, we observed that the angular intensities of the red and blue colors are close to Lambertian distribution, which can lead to a low color shift in all angles. From our study, the QD-enhanced micro-LEDs can effectively increase the brightness, the color stability, and the angular color match, and thus play a promising role in future micro-display technology.

Ultrahigh Power Density LuAG:Ce Green Converters For High‐Luminance Laser‐Driven Solid State Lighting

AbstractLu3Al5O12:Ce (LuAG:Ce) phosphor has been designed and fabricated into various forms of green fluorescent converters and plays a critical role in the field of solid‐state laser lighting. Phosphor in glass (PiG) and phosphor in glass film (PiGF) are expected to be viable strategies for high‐power and high‐brightness laser diode (LD) illumination due to their easy synthesis and low cost. In this study, LuAG:Ce‐PiG with an internal quantum efficiency of 90.5% is prepared by investigating the sintering conditions and combining with a borosilicate glass. It possesses a luminous flux (LF) of 584 lm and luminous efficiency (LE) of 225 lm W−1 @ 20 W mm−2. On this basis, LuAG:Ce‐PiG sapphire film (LuAG:Ce‐PiGSF) with high thermal conduction (10.26 W (m K) −1) is successfully sintered on the sapphire to obtain the LF of 833 lm and LE of 252 lm W−1 @ 36.36 W mm−2. The maximum tolerated power density can reach 45.45 W mm−2. In addition, when the color converters are placed in a commercial LD transmission module and continuously light for 24 h at 16.5 W, the relative light intensity only decreases by 14.15% and 12.82%, respectively. Therefore, it is believed that the work has promising applications in laser illumination and accelerating the development of LD lighting.

Tunable red/ blue emitting of Ca5(PO4)3F: Eu2+, Eu3+ and remote-excited color convertor for NUV-WLED

Eu2+/Eu3+ co-doped Ca5(PO4)3F (FAP) phosphors with tunable color of red/blue (R/B) emission were successfully synthesized by the two-step method for potential applications in light-emitting diodes (LED). Eu2+ (or Eu3+) single-doped and Eu2+/Eu3+ co-doped FAP all showed pure hexagonal FAP crystal with space group P63/m, indicating the occupation of Ca sites by Eu2+ and Eu3+ ions. Typically, Ca5(PO4)3F: Eu2+ phosphors exhibited a broad blue emission band at 451 nm under 293 nm excitation and Ca5(PO4)3F: Eu3+ samples emitted strong orange-red light at 596 nm, 615 nm and 620 nm under 394 nm excitation. Further, Eu2+/Eu3+ co-doped FAP phosphors obtained by the two-step method depicted the blue emission at 451 nm (Eu2+ ions) and the orange-red emission (Eu3+ ions) at 596 nm, 615 nm and 620 nm with an excitation wavelength of 365 nm (NUV). The tunable R/B ratio from 0.079 to 7.035 with various CIE chromaticity coordinate can be achieved by adjusting the recalcined temperature in the second step. Ca5(PO4)3F: Eu2+, Eu3+ sample can be packaged with green Lu3Al5O12 (LuAG) phosphors by 365 nm chip (1 W) and the cold white light with CIE chromaticity coordinate (0.2815, 0.3485) (CRI: 73, CCT: 7973 K) is achieving. Based on Ca5(PO4)3F: Eu2+, Eu3+ and 25B2O3-10SiO2-35ZnO-6Li2O-12La2O3-12WO3 (BS-glass) (in mol%) with strong mechanical strength as a great binder, the remote-excited color convertor (PiG: phosphor in glass) has been fabricated by screen printing technology for NUV-WLED application. Finally, by comparing the working temperature of PiG and pc-WLED at the same operating time, the working temperature of PiG was stable at 32 °C when remote excitation lighting was applied, which greatly avoided the phenomenon of “thermal quenching” for phosphors caused by high temperature under the operating of WLED. Thus, it was demonstrated that Eu2+ and Eu3+ co-doped Ca5(PO4)3F phosphors with tunable red/blue emitting would be a highly potential candidate for NUV-WLED.

Development of Three-Layered Composite Color Converters for White LEDs Based on the Epitaxial Structures of YAG:Ce, TbAG:Ce and LuAG:Ce Garnets

This work was dedicated to the development of novel types of composite phosphor converters of white LED, based on the epitaxial structures containing Y3Al5O12:Ce (YAG:Ce) and Tb3Al5O12:Ce (TbAG:Ce) single crystalline films, steeply grown, using the liquid-phase epitaxy method, onto LuAG:Ce single crystal substrates. The influence of Ce3+ concentration in the LuAG:Ce substrate, as well as the thickness of the subsequent YAG:Ce and TbAG:Ce films, on the luminescence and photoconversion properties of the three-layered composite converters were investigated. Compared to its traditional YAG:Ce counterpart, the developed composite converter demonstrates broadened emission bands, due to the compensation of the cyan-green dip by the additional LuAG:Ce substrate luminescence, along with yellow-orange luminescence from the YAG:Ce and TbAG:Ce films. Such a combination of emission bands from various crystalline garnet compounds allows the production of a wide emission spectrum of WLEDs. In turn, the variation in the thickness and activator concentration in each part of the composite converter allows the production of almost any shade from green to orange emission on the chromaticity diagram.

Face Mask Recognition based on Facial Feature and Skin Color Conversion

Face Mask Recognition based on Facial Feature and Skin Color Conversion

Medical image annotation and classification employing pyramidal feature specific lightweight deep convolution neural network

ABSTRACT Medical image annotation has significant potential to detect multiple tags. To detect specific tags and labels, most of the conventional learning algorithms took difficulty in matching the tag with corresponding region in the medical images. Hence, most of the medical image annotations fail to reproduce discrimination between various classes. In this research work to tackle medical image discrimination, we proposed a lightweight pyramidal feature-specific learning deep learning network. The proposed pyramidal feature-specific Lightweight Convolutional Neural Network (LDCNN) architecture for classifying local visual regions to annotate the classified region. By employing pyramidal learning, the proposed LDCNN align each medical image annotation with its region. The colour conversion makes low computation complexity, since the medical image exhibits degeneration by colour absorption. Hence, the interpretability and classification effectiveness increase. To evaluate the effectiveness and classification accuracy, we compare the proposed LDCNN with AlexNet and EfficientNet on benchmark datasets like MS-COCO, LC25000 and multiclass Kather datasets. Empirical experimental performance index obtained by the proposed LDCNN outperforms baseline convolutional neural network architecture. The proposed LDCNN achieves 99.6% accuracy, 98.4% sensitivity, 97.9% specificity and 99.1% F1 score. Hence, there is a steady improvement in medical annotation efforts and classification by our proposed lightweight feature-specific learning network.

Integrated transcriptomics and metabolomics analysis provide insight into anthocyanin biosynthesis for sepal color formation in Heptacodium miconioides.

Heptacodium miconioides Rehd., commonly known as "seven-son flower," is an ornamental species with a beautiful flower pattern and persistent sepals. Its sepals are of horticultural value, turning bright red and elongating in the autumn; however, the molecular mechanisms that cause sepal color change remain unclear. We analyzed the dynamic changes in anthocyanin composition in the sepal of H. miconioides at four developmental stages (S1-S4). A total of 41 anthocyanins were detected and classified into 7 major anthocyanin aglycones. High levels of the pigments cyanidin-3,5-O-diglucoside, cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, and pelargonidin-3-O-glucoside were responsible for sepal reddening. Transcriptome analysis revealed 15 differentially expressed genes involved in anthocyanin biosynthesis that were detected between 2 developmental stages. Of these, the high expression of HmANS was considered critical structural gene related to anthocyanin biosynthesis pathway in the sepal through co-expression analysis with anthocyanin content. In addition, a transcription factor (TF)-metabolite correlation analysis revealed that three HmMYB, two HmbHLH, two HmWRKY, and two HmNAC TFs exhibited a strong positive role in the regulation of the anthocyanin structural genes (Pearson's correlation coefficient > 0.90). Luciferase activity assay showed that HmMYB114, HmbHLH130, HmWRKY6, and HmNAC1 could activate the promoters of HmCHS4 and HmDFR1 genes in vitro. These findings increase our understanding of anthocyanin metabolism in the sepal of H. miconioides and provide a guide for studies involving sepal color conversion and regulation.

Patternable quantum dot color conversion film based on photolithography technique

This paper presents a patternable two-color quantum dot (QD) color conversion film based on photolithography technique. Toluene-assisted dispersion of QD powder with the best performance matching was selected from four typical dispersions by experimental comparison. On this basis, the color conversion film of QD was prepared by photolithography technique. The experimental results show that the height of the patternable QD microstructures has good consistency. At the same time, the monochromatic spectrum test shows that the spectral characteristics of QDs are not significantly affected by the photolithographic process. Therefore, the preparation methods described in this paper can provide a reference for related research.