Increase In Recombination Rate Research Articles

Role of oxygen vacancy enriched m-BiVO4/t-BiVO4 isotype heterojunction for enhanced photocatalytic degradation of rhodamine B dye and in ferroelastic to paraelastic phase transition

Mixed-phase isotype heterojunction oxide materials with superior photocatalytic activities have recently revealed a significant coupling between individual phases with controlled optical properties. Therefore, we focus on synthesizing a mixed-phase monoclinic-tetragonal (m-t) BiVO4 photocatalyst using hydrothermal method. The increased recombination rate of electron-hole (e−-h+) pairs limits the photocatalytic performance of monoclinic (m) BiVO4 photocatalysts. Therefore, effective spatial charge carrier separation can be improved by creating an isotype heterojunction between the phases m-BiVO4 and t-BiVO4. The precursor pH, mechanical grinding, and calcination temperature regulate the formation of m-t BiVO4. The phase fractions of the two phases in m-t BiVO4 sample are 85% monoclinic and 15% tetragonal. Herein, we demonstrate the optical properties and photocatalytic activity based on the crystal chemistry of m-BiVO4 and m-t BiVO4. Temperature-dependent Raman measurements suggest a second order ferroelastic monoclinic to paraelastic tetragonal phase transition above 530 K owing to optical phonon anharmonic coupling interactions. The small increase (5 °C) in Tc in m-t BiVO4 compared to m-BiVO4 is due to the coexistence of tetragonal and monoclinic phases. The optical band gap of m-t BiVO4 is larger than that of m-BiVO4. Additionally, the evaluation of BiVO4 photocatalytic activity over rhodamine-B (Rh-B) dye suggests that the m-t BiVO4 with 97.5% degradation efficiency is superior compared to m-BiVO4 with 89% degradation efficiency. This is because, the two phases (m and t) of BiVO4 form an isotype heterojunction interface, which results in a high charge separation efficiency, as demonstrated by photocurrent studies and electrochemical impedance spectroscopy. Moreover, oxygen vacancies tune the charge carrier dynamics through the modification of band edges. These findings regarding the isotype phase-junction mechanism provide possibilities for innovative ideas for highly efficient mixed-phase isotype heterojunction photocatalysts for wastewater remediation.

Genetic background affects the strength of crossover interference in house mice.

Meiotic recombination is required for faithful chromosome segregation in most sexually reproducing organisms and shapes the distribution of genetic variation in populations. Both the overall rate and the spatial distribution of crossovers vary within and between species. Adjacent crossovers on the same chromosome tend to be spaced more evenly than expected at random, a phenomenon known as crossover interference. Although interference has been observed in many taxa, the factors that influence the strength of interference are not well understood. We used house mice (Mus musculus), a well-established model system for understanding recombination, to study the effects of genetics and age on recombination rate and interference in the male germline. We analyzed crossover positions in 503 progeny from reciprocal F1 hybrids between inbred strains representing the three major subspecies of house mice. Consistent with previous studies, autosomal alleles from M. m. musculus tend to increase recombination rate, while inheriting a M. m. musculus X chromosome decreases recombination rate. Old males transmit an average of 0.6 more crossovers per meiosis (5.0%) than young males, though the effect varies across genetic backgrounds. We show that the strength of crossover interference depends on genotype, providing a rare demonstration that interference evolves over short timescales. Differences between reciprocal F1s suggest that X-linked factors modulate the strength of interference. Our findings motivate additional comparisons of interference among recently diverged species and further examination of the role of paternal age in determining the number and positioning of crossovers.

Interspecific transfer of genetic information through polyploid bridges

Hybridization blurs species boundaries and leads to intertwined lineages resulting in reticulate evolution. Polyploidy, the outcome of whole genome duplication (WGD), has more recently been implicated in promoting and facilitating hybridization between polyploid species, potentially leading to adaptive introgression. However, because polyploid lineages are usually ephemeral states in the evolutionary history of life it is unclear whether WGD-potentiated hybridization has any appreciable effect on their diploid counterparts. Here, we develop a model of cytotype dynamics within mixed-ploidy populations to demonstrate that polyploidy can in fact serve as a bridge for gene flow between diploid lineages, where introgression is fully or partially hampered by the species barrier. Polyploid bridges emerge in the presence of triploid organisms, which despite critically low levels of fitness, can still allow the transfer of alleles between diploid states of independently evolving mixed-ploidy species. Notably, while marked genetic divergence prevents polyploid-mediated interspecific gene flow, we show that increased recombination rates can offset these evolutionary constraints, allowing a more efficient sorting of alleles at higher-ploidy levels before introgression into diploid gene pools. Additionally, we derive an analytical approximation for the rate of gene flow at the tetraploid level necessary to supersede introgression between diploids with nonzero introgression rates, which is especially relevant for plant species complexes, where interspecific gene flow is ubiquitous. Altogether, our results illustrate the potential impact of polyploid bridges on the (re)distribution of genetic material across ecological communities during evolution, representing a potential force behind reticulation.

A Bird's-Eye View of Chromosomic Evolution in the Class Aves.

Birds (Aves) are the most speciose of terrestrial vertebrates, displaying Class-specific characteristics yet incredible external phenotypic diversity. Critical to agriculture and as model organisms, birds have adapted to many habitats. The only extant examples of dinosaurs, birds emerged ~150 mya and >10% are currently threatened with extinction. This review is a comprehensive overview of avian genome ("chromosomic") organization research based mostly on chromosome painting and BAC-based studies. We discuss traditional and contemporary tools for reliably generating chromosome-level assemblies and analyzing multiple species at a higher resolution and wider phylogenetic distance than previously possible. These results permit more detailed investigations into inter- and intrachromosomal rearrangements, providing unique insights into evolution and speciation mechanisms. The 'signature' avian karyotype likely arose ~250 mya and remained largely unchanged in most groups including extinct dinosaurs. Exceptions include Psittaciformes, Falconiformes, Caprimulgiformes, Cuculiformes, Suliformes, occasional Passeriformes, Ciconiiformes, and Pelecaniformes. The reasons for this remarkable conservation may be the greater diploid chromosome number generating variation (the driver of natural selection) through a greater possible combination of gametes and/or an increase in recombination rate. A deeper understanding of avian genomic structure permits the exploration of fundamental biological questions pertaining to the role of evolutionary breakpoint regions and homologous synteny blocks.

Second phase Cu2O boosted photocatalytic activity of fluorine doped CuO nanoparticles.

The photocatalytic activity of fluorine (F) doped CuO nanoparticles (NPs) prepared employing modified sol-gel process was investigated here in this study. Structural and elemental characterization using XRD and XPS data confirmed successful incorporation of F as dopant. F doping led to lattice distortion and reduced crystallinity with smaller crystallite size while promoting the emergence of Cu2O as the second phase. Morphological analysis showed irregularly shaped, fused particles with a decreasing particle size trend upon doping. Addition of hydrogen peroxide generated hydroxyl radicals (OH˙) under ultra-violet (UV) light, which effectively degrades pollutants by facilitating the photocatalytic kinetics. Photocatalytic activity of all the nanoparticles was examined against Rhodamine B (Rh B) dye and most efficient degradation (97.78%) was observed for 3 mol% F dopant concentration. The emergence of Cu2O phase for doping beyond 1 mol% F doped CuO might be the prime reason to enhance its degradation performance. Conversely, 5 mol% doping caused notable phase changes and decreased degradation rate (88.05%) due to increased recombination rate in presence of metallic copper. The ability of F doped CuO nanoparticles to disintegrate organic contaminants by producing reactive oxygen species when exposed to UV light suggests their potential effectiveness in applications such as dye degradation, water purification, and environmental sustainability.

Influence of Traps and Lorentz Force on Charge Transport in Organic Semiconductors.

Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps can lead to a decrease in charge carrier mobility and an increase in recombination rates, thereby ultimately affecting the overall performance of the device. It is therefore important to understand and mitigate the impact of traps on organic semiconductor devices. In this contribution, the influence of the capture and release times of trap states, recombination rates, and the Lorentz force on the net charge of a low-mobility organic semiconductor was determined using the finite element method (FEM) and Hall effect method through numerical simulations. The findings suggest that increasing magnetic fields had a lesser impact on net charge at constant capture and release times of trap states. On the other hand, by increasing the capture time of trap states at a constant magnetic field and fixed release time, the net charge extracted from the semiconductor device increased with increasing capture time. Moreover, the net charge extracted from the semiconductor device was nearly four and eight times greater in the case of the non-Langevin recombination rates of 0.01 and 0.001, respectively, when compared to the Langevin rate. These results imply that the non-Langevin recombination rate can significantly enhance the performance of semiconductor devices, particularly in applications that require efficient charge extraction. These findings pave the way for the development of more efficient and cost-effective electronic devices with improved charge transport properties and higher power conversion efficiencies, thus further opening up new avenues for research and innovation in this area of modern semiconductor technology.

Photostability of blue phosphorescent films on plasmonic surfaces.

Organometallic phosphors are an important class of emissive materials used in high-efficiency organic light-emitting devices. However, problems of low photostability arise for blue-emitting phosphors due to chemical and environmental degradation and triplet quenching processes. Various approaches have been developed to improve the photostability of such phosphors, including the design of new organometallic molecules and control of host-dopant composition in thin films. Here, we demonstrate a different approach for improving the photostability of blue organometallic phosphors that uses localized surface plasmon resonances to increase the triplet recombination rate. The increased recombination rate improves the photostability of the phosphor due to the reduction in triplet quenching pathways. We show that the lifetime of phosphorescence is decreased significantly by nanoparticle-based plasmonic surfaces, which improves the photostability of the blue organometallic phosphor by up to a factor of 3.6. Other plasmonic surfaces are also tested and exhibit less significant photostability improvements due to a reduced spectral overlap of the plasmonic modes with the emitter and lower mode confinement. The use of plasmonic surfaces to improve phosphor photostability at blue wavelengths is distinct from other approaches because it involves modification to the local electromagnetic environment of the phosphor rather than modifications to the phosphor molecular structure or the emitting material composition.

Carrier Confinement in Ultraviolet-C AlGaN Light-Emitting Diodes

We have numerically analyzed three different light-emitting diodes (LEDs) namely LED S1, LED S2, and LED S3 in the ultraviolet (UV) region. The band diagram, radiative recombination, and carrier distribution have been studied for LED S2 and LED S3 in comparison to LED S1. Our simulation study has shown that both the proposed structures i.e., LED S2 and LED S3 prove to be better strategies for impeding electron overflow and improving hole inflow. LED S2 and LED S3 have been found to have a reduced efficiency droop at 200 A cm−2 than reference LED S1. Increase in carrier concentration and radiative recombination rate have directly affected the internal quantum efficiency (IQE) of LED S2 and LED S3. The emission spectra of proposed LEDs have increased markedly as compared to LED S1.

Revealing Ultrafast Carrier Dynamics of Hybrid Perovskites at Various Stages of Nucleation and Growth Kinetics

AbstractWith hybrid organic–inorganic perovskites expanding their technological reach, from photovoltaic solar cells that operate at low carrier densities (1011 − 1013 cm−3) to light‐emitting diodes and lasers that operate at higher carrier densities (1013 − 1019 cm−3), it is critical to know how microstructure dictates carrier dynamics at varying injected carrier densities. For fabrication at scale, it is equally critical to know how quickly during the growth process do hybrid perovskites develop their characteristic optoelectronic properties. This work reports on a facile fabrication method that “freezes” different stages of nucleation and growth kinetics of prototypical hybrid perovskite on the same substrate—providing a unique strategy to assess differences in optoelectronic properties and carrier dynamics from nascent nucleating microcrystals to large‐grain thin films. The solution‐processed fabrication technique, optimized to control the nucleation density of an intermediate phase, successfully decouples the nucleation and growth steps that lead to large‐grain thin films. Ultrafast broadband absorption microscopy finds that the nucleating microcrystals already possess the optoelectronic properties of hybrid perovskites and share similar femtosecond‐to‐nanosecond dynamics as large‐grain thin films. When compared to the large‐grain thin films, the confining microcrystals exhibit enhanced carrier interactions, marked by an increase in bimolecular and Auger recombination rates.

Feasibility of Integrating Bimetallic Au-Ag Non-Alloys Nanoparticles Embedded in Reduced Graphene Oxide Photodetector

To coordinate the resonant wavelength of the plasmonic nanoparticles (NPs), the emission band of the reduced graphene oxide (rGO) photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in the device. In contrast to monometallic NPs, where limits the dimensions and extended resonant wavelength, we integrated an Au-Ag bimetallic NPs (BMNPs) to enable resonance tuning at the longer wavelength at the excitation source of 785 nm. These features showed an increase in radiative recombination rates as well as the quantum yield efficiency of the device. The BMNPs were produced from the dewetting process of 600 °C and 500 °C, both at 1 min after the deposition thickness layer of Au (8 nm) and Ag (10 nm) on the Si substrate using the electron-beam evaporation process. Our BMNPs-rGO photodetector exhibited the responsivity of 2.25 · A W−1, Jones of specific detectivity of 2.45×1011Jones, and external quantum efficiency (EQE) of 356%. The rise time and fall time for the photodetector were 32 ns and 186 ns, respectively. This work provided an essential information to enable the versatile plasmon-enhanced application in 2-dimensional (2D) material optoelectronic devices.

The coordinated regulation of early meiotic stages is dominated by non-coding RNAs and stage-specific transcription in wheat.

Reproductive success hinges on precisely coordinated meiosis, yet our understanding of how structural rearrangements of chromatin and phase transitions during meiosis are transcriptionally regulated is limited. In crop plants, detailed analysis of the meiotic transcriptome could identify regulatory genes and epigenetic regulators that can be targeted to increase recombination rates and broaden genetic variation, as well as provide a resource for comparison among eukaryotes of different taxa to answer outstanding questions about meiosis. We conducted a meiotic stage-specific analysis of messenger RNA (mRNA), small non-coding RNA (sncRNA), and long intervening/intergenic non-coding RNA (lincRNA) in wheat (Triticum aestivum L.) and revealed novel mechanisms of meiotic transcriptional regulation and meiosis-specific transcripts. Amidst general repression of mRNA expression, significant enrichment of ncRNAs was identified during prophase I relative to vegetative cells. The core meiotic transcriptome was comprised of 9309 meiosis-specific transcripts, 48 134 previously unannotated meiotic transcripts, and many known and novel ncRNAs differentially expressed at specific stages. The abundant meiotic sncRNAs controlled the reprogramming of central metabolic pathways by targeting genes involved in photosynthesis, glycolysis, hormone biosynthesis, and cellular homeostasis, and lincRNAs enhanced the expression of nearby genes. Alternative splicing was not evident in this polyploid species, but isoforms were switched at phase transitions. The novel, stage-specific regulatory controls uncovered here challenge the conventional understanding of this crucial biological process and provide a new resource of requisite knowledge for those aiming to directly modulate meiosis to improve crop plants. The wheat meiosis transcriptome dataset can be queried for genes of interest using an eFP browser located athttps://bar.utoronto.ca/efp_wheat/cgi-bin/efpWeb.cgi?dataSource=Wheat_Meiosis.

Re-evaluating Homoploid Reticulate Evolution in Helianthus Sunflowers.

Sunflowers of the genus Helianthus are models for hybridization research and contain three of the best-studied examples of homoploid hybrid speciation. To understand a broader picture of hybridization within the annual sunflowers, we used whole-genome resequencing to conduct a phylogenomic analysis and test for gene flow between lineages. We find that all annual sunflower species tested have evidence of admixture, suggesting hybridization was common during the radiation of the genus. Support for the major species tree decreases with increasing recombination rate, consistent with hybridization and introgression contributing to discordant topologies. Admixture graphs found hybridization to be associated with the origins of the three putative hybrid species (Helianthus anomalus, Helianthus deserticola, and Helianthus paradoxus). However, the hybridization events are more ancient than suggested by previous work. Furthermore, H. anomalus and H. deserticola appear to have arisen from a single hybridization event involving an unexpected donor, rather than through multiple independent events as previously proposed. This means our results are consistent with, but not definitive proof of, two ancient independent homoploid hybrid speciation events in the genus. Using a broader data set that covers the whole Helianthus genus, including perennial species, we find that signals of introgression span the genus and beyond, suggesting highly divergent introgression and/or the sorting of ancient haplotypes. Thus, Helianthus can be viewed as a syngameon in which largely reproductively isolated species are linked together by occasional or frequent gene flow.

Tailoring the performance of GaN-based yellow light-emitting diodes

Efficient yellow InGaN light-emitting diodes (LEDs) have been a challenge for the researchers. To achieve yellow emission, high indium composition is necessary. However, high indium composition comes with its own challenges. In our work, the performance of InGaN yellow light emitting diodes is improved by using quaternary (AlInGaN) quantum barriers and ternary (AlGaN) quantum barriers in the conventional InGaN/GaN LED. We show that employing AlGaN quantum barriers in the light-emitting diodes significantly increases the concentration of electrons as well as holes, resulting in a 47% increase in radiative recombination rate than the conventional yellow LED. Additionally, the efficiency droop is significantly reduced in our proposed LEDs.

Analysis of different buffer layers on CuO based solar cells using SCAPS-1D

We have used SCAPS-1D to do simulations on CuO based solar cells using ZnO, TiO2, CdS and ZnSe as buffer layers. The solar cell characteristics are analysed by varying different material properties. The CuO/ZnO based solar cell showed highest efficiency ~20%. The interface defect however impacts the efficiency of this solar cell significantly. The interface defect and buffer layer thickness has shown little impact on the TiO2 and ZnSe buffer layer based solar cell. Further, we have optimized the impact of absorber layer thickness, carrier concentration and absorber defect as well. The effect of buffer layer thickness and electron affinity has also been investigated. Further, we have tried to understand the effect of temperature on the performance of these solar cells. The increase in temperature has resulted in decreased efficiency attributing to increased recombination rate.

Insights into the impact of defect states and temperature on the performance of kesterite-based thin-film solar cells

In this study, we explore the influence of defect states density and operating temperatures on the performance of kesterite-based (CZT(S,Se)) solar cells such as CZTS, CZTSe, and CZTSSe. SCAPS codes were used as a constructive technique in modeling all structures. The CZT(S,Se) structures were modified by incorporating a p-Mo(S,Se)2 interfacial layer between the back contact and the absorber. Interestingly, only a 100 nm thick layer of p-Mo(S,Se)2 can establish a quasi-ohmic configuration at a CZT(S,Se)/Mo heterojunction, which was demonstrated by an increase in the slope of the J-V characteristics. In the active layer region, a series of systematic simulations were conducted depicting the response of CZTSSe/MoSSe structures to defect density states ranging from 1013 cm-3 to 1017 cm-3. The recombination behavior of CZTSSe/MoSSe solar cells is significantly superior to those made of CZTS/MoS2 or CZTSe/MoSe2, with a minimum increase in recombination current of 2.03 mA/cm2. The increased recombination rates are attributed to a shorter minority carrier lifetime at the buffer-absorber interface due to a reduced diffusion length between electrons and holes. Additionally, the photovoltaic parameters of the CZT(S,Se) structures were examined over a wide temperature range, from 275 K to 475 K, including open-circuit voltage (Voc), short circuit current (Jsc), fill factor (FF), and power conversion efficiency (PCE). A CZTS/MoS2-based structure exhibited the most stable performance at elevated temperatures up to 395 K with minimum degradation in PCE of approximately 2% compared to other solar cells. As a result, the voltage variation to temperature coefficients obtained for the CZTS and CZTSe solar cells were − 0.75 mV/K and − 1.2 mV/K, respectively. These findings support the use of CZTS/MoS2 structures in the development of photovoltaic modules that are capable of operating at high temperatures.

Disappearance of the Polar Cap Ionosphere During Geomagnetic Storm on 11 May 2019

AbstractMulti‐instrument data from Jang Bogo Station (JBS) in Antarctica were utilized to study ionospheric responses to the 11 May 2019 moderate geomagnetic storm. These include Vertical Incident Pulsed Ionospheric Radar (VIPIR)/Dynasonde, Fabry‐Perot Interferometer (FPI), GPS vertical total electron content (vTEC), and magnetometer. The VIPIR/Dynasonde observed long‐lasting (>11 hr) severe depletion of the electron density in the F‐region ionosphere over JBS. During the depletion interval, GPS TEC also correspondingly decreased, FPI neutral temperature was significantly enhanced, and the polar magnetic field variations showed positive and negative excursions in the Y (east) and Z (vertical) components, respectively. GK‐2 A satellite, located ∼2.5 hr west of JBS, observed negative magnetic field perturbations in the azimuthal BD component at geosynchronous orbit during the depletion of ionospheric plasma. Such a BD perturbation at geosynchronous orbit is due to the field‐aligned currents flowing out of the ionosphere. From these observations we suggest that transpolar ionospheric currents connected to the field‐aligned currents flowing on a substorm wedge‐shaped circuit act as a source of polar atmospheric heating during the moderate geomagnetic storm interval and that elevated heavy molecular gases (O2 and N2) by atmospheric heating contribute to the electron density depletion via increased recombination rate.

Modelling the ionization state of Type Ia supernovae in the nebular phase

ABSTRACT The nebular spectra of Type Ia supernovae (⪆100 d after explosion) consist mainly of emission lines from singly and doubly ionized Fe-group nuclei. However, theoretical models for many scenarios predict that non-thermal ionization leads to multiply ionized species whose recombination photons ionize and deplete Fe+, resulting in negligible [Fe ii] emission. We investigate a method to determine the collisional excitation conditions from [Fe ii] line ratios independently from the ionization state and find that it cannot be applied to highly ionized models due to the influence of recombination cascades on Fe+ level populations. When the ionization state is artificially lowered, the line ratios (and excitation conditions) are too similar to distinguish between explosion scenarios. We investigate changes to the treatment of non-thermal energy deposition as a way to reconcile overionized theoretical models with observations and find that a simple work function approximation provides closer agreement with the data for sub-Mch models than a detailed Spencer–Fano treatment with widely used cross-section data. To quantify the magnitude of additional heating processes that would be required to sufficiently reduce ionization from fast leptons, we artificially boost the rate of energy loss to free electrons. We find that the equivalent of as much as an eight times increase to the plasma loss rate would be needed to reconcile the sub-Mch model with observed spectra. Future studies could distinguish between reductions in the non-thermal ionization rates and increased recombination rates, such as by clumping.

Unraveling the Role of Energy Band Alignment and Mobile Ions on Interfacial Recombination in Perovskite Solar Cells

A key limitation in perovskite solar cell (PSC) performance is suboptimal electronic properties at the perovskite–transport layer (TL) interfaces, which result in parasitic nonradiative recombination. Interface recombination depends on the concentration of recombination‐active defects, but as a recombination event requires both an electron and a hole, the magnitude and sign of charge accumulation at the perovskite–TL heterojunctions are also critical. Here, we employ a well‐established numerical ion‐electron drift‐diffusion model of PSCs to illustrate how the work function of the transport layer is an important factor in determining the total recombination activity at the perovskite interfaces. We show that the equilibrium electrostatics of the perovskite–TL heterojunctions, which are determined by the work function difference between the two materials, can result in increased recombination rates for any given concentration of interface defects. As a case study, we compare PSCs incorporating a NiOX hole transport layer with those with a spiro‐OMeTAD. We show that the work function of NiOX can induce greater electron accumulation at the perovskite–NiOX interface, which leads to increased interface recombination. Finally, a higher ion concentration is found to be beneficial to overall device performance by displacing accumulated electrons or holes at the TL interfaces and thus reducing recombination rates.

Genetic structure analysis in several populations of cattle using SNP genotypes

Parameters such as effective population size (Ne), runs of homozygosity (ROH), and inbreeding based on ROH (FROH) can give new insight into the level of genetic diversity for the population under selection. This research aimed to measure the extent of linkage disequilibrium (LD), effective population size (Ne), Haplotype Block Structure, and runs of homozygosity (ROHs) in several populations of cattle using SNP genotypes. In this study, that the average r 2 decreased with the increasing distance of SNP pairs. A general decrease in Ne can be seen for all four populations, indicating a loss of genetic diversity. The Iranian Holstein had the lowest level of genomic inbreeding at an ROH of 1, 5, 10 Mb, while the French Holstein had the highest. The maximum number of ROH is seen at a distance of less than 1 Mb, and the lowest number of ROH is seen at a distance of 10 Mb. The number of ROH decreases with increasing distance due to the increased recombination rate. This is a concern as an increase in inbreeding leads to a reduction in the effective population size, which was also evident in the study populations.

Enhanced and angle dependent blue fluorescence of perovskite nanocrystals on three typical photonic crystals

Photonic crystals (PCs) are promising structures for the modulation and enhancement of fluorescent emissions, however, there is still a lack of systematic investigation on the fluorescence of perovskite nanocrystals (PNCs) coupling with different PCs. In this work, the blue emitting PNCs are coated on three typical PCs, i.e. biological Menelaus butterfly wings (MBWs), hexagonal closely-packed SiO2 nanoparticles, and TiO2 nanotubes array, which show fluorescence enhancement factors of 5.14, 3.38, and 3.43, respectively. The fluorescence enhancement is jointly attributed to the increased recombination rate caused by the near field effect and the enhanced extraction of emission due to the overlap of the leaky mode of the PCs with the emission wavelength of the PNCs. The higher enhancement factor of the MBWs is ascribed to the fluorescent proteins and melanin. Moreover, fluorescence intensity of the PNCs on all the three PCs strongly depends on the observation angle, which will enable their applications in anti-peeping screen and anti-counterfeiting pattern.