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Facile method for the preparation of high-performance photodetectors with a GQDs/perovskite bilayer heterostructure
摘要： A high-performance nitrogen doped graphene quantum dots (GQDs)/all-inorganic (CsPbBr3) perovskite nanocrystals (NCs) heterostructure photodetector was fabricated on a quartz substrate, using the low cost spin coating technique followed by hot plate annealing. The GQDs/CsPbBr3 NCs heterostructure photodetector exhibits a high overall performance with a photoresponsivity of 0.24 AW?1, on/off ratio of 7.2 × 104, and specific detectivity of up to 2.5 × 1012 Jones. The on/off ratio of the hybrid device was improved by almost ten orders of magnitude, and the photoresponsivity was enhanced almost three times compared to the single layer perovskite NCs photodetector. The performance enhancement of the hybrid device was due to its highly efficient carrier separation at the GQDs/CsPbBr3 NCs interface. This results from the coupling of the GQDs layer, which efficiently extracts and transports the photogenerated carriers, with the CsPbBr3 NCs layer, which has a large absorption coefficient and high quantum efficiency. The interfacial charge transfer from the CsPbBr3 NCs to the GQDs layer was demonstrated by the quenching in the photoluminescence (PL) spectra, and the fast-average decay time in the time-resolved photoluminescence (Trpl) spectra of the hybrid photodetector. Moreover, the performance-enhancement mechanism of the hybrid GQDs/CsPbBr3 photodetector was elucidated by analyzing the band alignment of the GQDs and CsPbBr3 under laser illumination.
关键词： Carrier separation,Charge transfer,CsPbBr3 nanocrystals,Photodetectors,Graphene quantum dots
更新于2025-09-12 10:27:22
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Porous single-wall carbon nanotube templates decorated with all-inorganic perovskite nanocrystals for ultra-flexible photodetectors
摘要： As an inevitable optoelectronic material with unique properties, halide perovskites attracted increasing attention in recent years. Meanwhile, hybridization of nanostructured perovskites with one-dimensional (1D) or two-dimensional (2D) functional materials has exhibited unique applications in nanotechnology. In this communication, a highly conducting porous single-wall carbon nanotube (p-SWCNT) template decorated with phase-pure CsPbBr3 nanocrystals by simple solution-phase technique was demonstrated, and the ultra-flexible photodetector Au/p-SWCNT:CsPbBr3/Au showed high sensitivity even in highly bending state. Also, the mechanism of wetting CsPbBr3 along p-SWCNT and the detailed fabrication process for ultra-flexible photodetectors were highlighted. The direct contact (in-situ) on p-SWCNT by crystallization of perovskite precursor can enhance the charge transfer at their interface effectively. At applied bias of +5 V, the optimized photodetector Au/p-SWCNT:CsPbBr3/Au exhibits a maximum photoresponsivity of 41.0 AW-1 with a specific detectivity of 1.67×1012 Jones under an incident 232 μW/cm2 520 nm illumination. In addition, it exhibits excellent mechanical and electrical properties even under high strain (i.e. bending angle up to -17°) and recovers the original performance after repeated bending cycles upto 1000 times. Our experimental results showed that such a hybrid materials provide a promising method for rigid and flexible optoelectronic devices.
关键词： Porous single-wall carbon nanotube (p-SWCN),inorganic perovskite nanocrystals,flexible photodetector,CsPbBr3,visible light photodetector
更新于2025-09-12 10:27:22
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Swelling‐Deswelling Microencapsulation‐Enabled Ultrastable Perovskite?Polymer Composites for Photonic Applications
摘要： Metal halide perovskite nanocrystals are emerging as novel optoelectronic materials. Owing to their excellent optical and electronic properties such as tunable band gap, narrow-band emission and high charge mobility, they are quite promising in various fields including liquid-crystal display backlighting, solid-state lighting and other energy conversion applications. However, the intrinsic low formation energy makes them vulnerable to external stimulus, e. g. water, oxygen, heat, etc. Among many methods, swelling-deswelling microencapsulation emerges as one of the most promising strategies to improve their stability. Herein, recent developments and future research directions in swelling-deswelling microencapsulation-enabled ultrastable perovskite(cid:0) polymer composites are summarized. We believe this strategy has great potential to deliver successful perovskite-based commercial products for many photonics applications.
关键词： ultra-stable,perovskite nanocrystals,polymer,swelling-deswelling microencapsulation,photoluminescence
更新于2025-09-12 10:27:22
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Charge Transport between Coaxial Polymer Nanorods and Grafted All-Inorganic Perovskite Nanocrystals for Hybrid Organic Solar Cells with Enhanced Photoconversion Efficiency
摘要： The versatile optoelectronics properties of perovskite nanocrystals (NCs) have provided a strong surge for their utilization in different classes of solar cells, organic photovoltaic (OPV) systems being no exception. In an unprecedented approach, a hybrid solar cell with CsPbBr1.5I1.5 NCs strategically grafted on poly(3-hexylthiophene-2,5-diyl) (P3HT) nanorods (NRs) is shown to have a photoconversion efficiency (PCE) of 9.72 ± 0.4 %, with only 1.5 wt% NCs. The improvement is twice more than the P3HT:PCBM reference devices (4.09 ± 0.2 %). The choice of NC composition is validated by Density Functional Theory (DFT) calculations which show decent charge carrier mobility in CsPbBr1.5I1.5, besides having better stability than CsPbI3, making CsPbBr1.5I1.5 NCs suitable contender for hybrid device architecture. A trivial blending of the NCs in P3HT:PCBM matrix results in their non-uniform distribution, escalating charge carrier trapping, albeit maintaining a device efficiency of 8.07 ± 0.3 % with 1 wt% NCs. Uniform NC grafting is propitious over inhomogeneous blending since CsPbBr1.5I1.5 NCs not only act as additional light harvesters, but their chemical grafting onto the P3HT NRs improves the charge transport by creating better charge percolation pathways. The higher crystallinity of the P3HT NRs than P3HT also helps in reducing the trap states.
关键词： P3HT nanorods,charge transport,perovskite nanocrystals,photoconversion efficiency,hybrid solar cells
更新于2025-09-12 10:27:22
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New Antimony-Based Organic–Inorganic Hybrid Material as Electron Extraction Layer for Efficient and Stable Polymer Solar Cells
摘要： Hybrid organic-inorganic materials are a new class of material used as interfacial layers in polymer solar cells. A hybrid material, composed of antimony as inorganic part and diaminopyridine as organic part, is synthesized and described as a new material for electron extraction layer in polymer solar cells and compared to the recently demonstrated hybrid materials using bismuth instead of antimony. The hybrid compound is solution-processed onto the photoactive layer based on a classical blend, composed of PTB7-Th low bandgap polymer as donor mixed with PC70BM fullerene as acceptor material. By using a regular device structure and an aluminum cathode, the solar cells exhibited a power conversion efficiency of 8.42%, equivalent to the reference device using ZnO nanocrystals as interfacial layer, and strongly improved compared to bismuth-based hybrid material. The processing of extraction layers up to a thickness of 80 nm of such hybrid material reveals that the change from bismuth to antimony has strongly improved the charge extraction and transport properties of the hybrid materials. Interestingly, nanocomposites made of the hybrid material mixed with ZnO nanocrystals in a 1:1 ratio further improved the electronic properties of the extraction layers, leading to power conversion efficiency of 9.74%. This was addressed to a more closely packed morphology of the hybrid layer, leading to further improved electron extraction. It is important to note that these hybrid electron extraction layers, both pure and ZnO-doped, also greatly improved the stability of solar cells, both under dark storage in air and under lighting under inert atmosphere compared to solar cells treated with ZnO intermediate layers.
关键词： solar cell,morphology,hybrid material,electron extraction,nanocrystals,interfacial layer
更新于2025-09-12 10:27:22
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Integrated Effects of Near-field Enhancement-Induced Excitation and Surface Plasmon-Coupled Emission of Elongated Gold Nanocrystals on Fluorescence Enhancement and the Applications in PLEDs
摘要： Localized surface plasmon resonance (LSPR) field enhancement effects of noble metallic nanoparticles can be exploited to enhance the performance of diverse luminescent materials and devices, in which the spectral proximity plays an important role in increasing near-field enhancement-induced excitation (NFEE) and surface plasmon-coupled emission (SPCE) efficiencies. In this work, we propose a scheme simultaneously utilizing the transversal and longitudinal SPR bands of elongated gold nanocrystals to match with the excitation and emission wavelengths of emitters, respectively, to achieve the most efficient enhancement. To demonstrate the idea, four types of gold nanoparticles (AuNPs, diameter=20 nm), gold nanorods (AuNRs, length/width=80/40 nm; 90/30 nm) and gold nanobipyramids (AuNBPs, length/width=80/40 nm) were employed as the plasmonic nanoantennas, according to spectral characteristics of the classic poly(2-methoxy-5-(2′-ethyl-hexoxy)-1,4-phenylene-vinylene) (MEH-PPV) chosen as the emitter. Due to the double SPR bands of both AuNBPs (80/40 nm) and AuNRs (80/40 nm) overlapping well with the excitation and emission wavelengths of MEH-PPV, maximum 2.2 and 2.1 times enhancement in photoluminescence intensity was observed, respectively. This is attributed to the integrated effects of NFEE and SPCE that synchronously accelerate the excitation and radiation rate as evidenced by steady-state and time-resolved photoluminescence measurements. Further, above plasmonic nanoantennas were incorporated into the polymer light-emitting diodes (PLEDs), in which AuNBPs (80/40 nm)- and AuNRs (80/40 nm)-mediated devices exhibited approximately 2.3 and 2.1 times enhancement in luminance, and 2.0 and 1.9 times enhancement in luminous efficiency compared with the pristine one, respectively. And more notably, it is firstly demonstrated that the sharp-tip AuNBPs generating stronger local electric field compared to AuNRs can efficiently enhance PLEDs performance, showing a promising prospect for the development of high-performance red and near-infrared electroluminescence devices.
关键词： emission enhancement,SPR effects,PLEDs,Gold nanocrystals,spectral proximity
更新于2025-09-12 10:27:22
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Machine Learning Accelerates Discovery of Optimal Colloidal Quantum Dot Synthesis
摘要： Colloidal quantum dots (CQDs) allow broad tuning of the bandgap across the visible and near-infrared spectral regions. Recent advances in applying CQDs in light sensing, photovoltaics, and light emission have heightened interest in achieving further synthetic improvements. In particular, improving monodispersity remains a key priority in order to improve solar cells’ open-circuit voltage, decrease lasing thresholds, and improve photodetectors’ noise-equivalent power. Here we utilize machine-learning-in-the-loop to learn from available experimental data, propose experimental parameters to try, and, ultimately, point to regions of synthetic parameter space that will enable record-monodispersity PbS quantum dots. The resultant studies reveal that adding a growth-slowing precursor (oleylamine) allows nucleation to prevail over growth, a strategy that enables record-large-bandgap (611 nm exciton) PbS nanoparticles with a well-defined excitonic absorption peak (half width at half max (HWHM) of 145 meV). At longer wavelengths, we also achieve improved monodispersity, with HWHM of 55 meV at 950 nm and 24 meV at 1500 nm, compared to the best published to date values of 75 meV and 26 meV, respectively.
关键词： machine learning,PbS,Bayesian optimization,synthesis,nanocrystals,colloidal quantum dots
更新于2025-09-12 10:27:22
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Ultrafast Plasmon Dynamics and Hole–Phonon Coupling in NIR Active Nonstoichiometric Semiconductor Plasmonic Cu <sub/> 2– <i>x</i> </sub> S Nanocrystals
摘要： Nonstoichiometric Cu2?xS nanocrystals (NCs) have been synthesized by hot-injection method after changing the copper to sulfur ratio. Optical studies confirmed well-defined localized surface plasmon resonance (LSPR) absorbance band from near-infrared to mid-infrared arising due to p-type hole vacancy in the doped semiconductor. Carrier concentrations of the Cu2?xS NCs are calculated to be on the order of ～1021 cm?3 after following the Drude model, which is one order of magnitude lower as compared to the metallic (Au/Ag) system. To understand ultrafast plasmon dynamics of Cu2?xS NCs, femtosecond broadband (visible?near IR) pump?probe spectroscopy has been employed. Ultrafast plasmon dynamics of the Cu2?xS NCs have been monitored after changing composition (copper to sulfur ratio), pump wavelength, and laser intensity. At moderate pump power hole?phonon relaxation time constant has been observed to be in the range of 240?440 fs for Cu2?xS NCs depending upon pump wavelengths (400, 800 nm). From the ultrafast transient data, hole?phonon coupling constant (G) has been determined in the range (1.6?2.7) × 1010 J K?1 s?1 cm?3 for Cu2?xS NCs at different excitation wavelengths, which is also one order lower as compared to the metallic system. We have proposed a new mechanistic scheme for hot carrier relaxation dynamics, in accordance with the two-temperature model (TTL) as reported in literature for plasmon dynamics.
关键词： Nonstoichiometric Cu2?xS nanocrystals,femtosecond broadband pump?probe spectroscopy,localized surface plasmon resonance,hole?phonon coupling constant,two-temperature model,Drude model
更新于2025-09-12 10:27:22
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Doped quaternary metal chalcogenides Cu2ZnSnS4 nanocrystals as efficient light harvesters for solar cell devices
摘要： In this study, we report highly stable photoactive quaternary metal chalcogenide Cu2ZnSnS4 nanocrystals synthesis from low cost, ecofriendly, non-toxic and earth-abundant elements for photovoltaic devices. Their electro-optical properties such as, tunable band gap, high-absorption coefficient and wide absorption window make them highly suitable materials to be utilized as absorber layer and counter electrode in various types of solar cells. For this purpose, first we synthesized Cu2ZnSnS4 nanocrystals by colloidal, co-precipitation, wet chemical and hydrothermal methods using stabilizing agents under variable reaction conditions. Afterwards, hydrothermal method was employed to synthesize nanocrystals of Cu2CoSnS4, Cu2FeSnS4, Cu2SrSnS4 and Cu2NiSnS4 by replacing Zn with Co, Fe, Sr and Ni metals. The UV–Vis absorption spectra indicate the nanocrystals can absorb entire visible region of electromagnetic radiation and their band gaps range from 1.5 to 1.7 eV. The X-ray diffraction (XRD) patterns confirm the formation of kieserite phase of all nanocrystals with a crystallite size of approximately 6–10 nm. These nanocrystals are coated on surface of the synthesized ZnO nanoparticles to study their application as absorbing layer in quantum dots-sensitized solar cells (QDSSCs). Moreover, they were adsorbed on ITO substrate to study their utilization as counter electrode of dye-sensitized solar cells (DSSCs). The solar cells exhibit efficiencies of 1.2–1.8%, which prove the synthesized nanocrystals can perform excellent role as light absorber and counter electrode in any kind of solar cell device.
关键词： solar cell devices,light harvesters,photovoltaic devices,dye-sensitized solar cells,quantum dots-sensitized solar cells,Cu2ZnSnS4 nanocrystals
更新于2025-09-12 10:27:22
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All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr3 colloidal nanocrystals as carriers-extracting layer
摘要： Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. Especially, all-inorganic CsPbX3 (X=Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed broadband photodetectors ITO/ZnO/CsPbBr3/PbS/Au with high-performance were presented. The role of CsPbBr3 QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from UV-IR broadband trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au are enhanced, but the trilayer photodetector ITO/ZnO(80nm)/CsPbBr3(50nm)/PbS(150nm)/Au showed a maximum specific detectivity (D*) of 1.73×1012 Jones with a responsivity (R) of 5.31 A/W under 6.8 mW/cm2 405 nm illumination. However, another trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au showed a maximum D* of 8.3×1012 Jones with a R of 35 A/W under 1.6 mW/cm2 980 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high-performance.
关键词： broadband photodetectors,all-solution-processed heterojunction,Colloidal quantum dots (CQDs),CsPbBr3 perovskite nanocrystals,carrier-extraction layer
更新于2025-09-12 10:27:22