Average oxygen content (c_o) and radial oxygen variation (ROV) are two quality specifications of semiconductor-grade Czochralski (Cz) silicon. In this paper, an optimization model combing two artificial neural networks (ANNs) with a non-dominated sorting genetic algorithm (NSGA-Ⅱ) is proposed to obtain optimal crystal growth parameters. Four parameters, namely crystal rotation rate, crucible rotation rate, pulling rate, and thickness of bottom insulation, are selected as input features of the ANNs and optimized in the proposed model. The optimization model aims at two objectives: controlling average oxygen content within the qualified range and reducing ROV. During the process, parameter settings satisfy the Voronkov criterion to ensure a micro-defect-free Cz silicon. First, a computational fluid dynamics (CFD) model we developed is used to generate data for training ANNs to predict v/G, c_o and ROV. Then, the well-trained ANNs are integrated with NSGA-Ⅱ to perform multi-objective optimization and generate Pareto optimal solutions. The optimal candidate is chosen on the Pareto front according to demands. Finally, the optimization model is validated through CFD results. Our findings reveal an inverse relationship between ROV and oxygen content. By employing this method, we are able to optimize the parameters to meet the desired specifications for both ROV and oxygen content in 300 mm Cz silicon growth.

Enhancing the photodetection capabilities of organic photodetectors (OPDs) is crucial for advancing applications in medical monitoring, optical communications, image sensing, and robotics, where a strong, focused peak response at a specific designed wavelength is essential for improving sensitivity, wavelength selectivity, and resolution in imaging systems. By controlled integration of ZnO layers within PBDBT:BTP-4F-based OPDs to form a Fabry-Perot optical cavity, we developed a cost-effective approach to fabricating highly sensitive OPDs by utilizing PBDBT:BTP-4F organic bulk heterojunctions, and extended its detection wavelengths into the near-infrared (NIR) range. Our design integrates a single silver (Ag) layer that significantly enhances peak detection at a wavelength of 830 nm, resulting in a remarkably narrow full-width at half maximum (FWHM) wavelength of 30 nm and yielding a photoresponse ten times greater than that of non-resonant devices. Furthermore, by varying the thickness of the ZnO layer from 77 nm to 620 nm, we achieve high spectral tunability, allowing fine adjustments of the resonant peak across a spectrum ranging from ultraviolet (UV) and visible to NIR wavelengths. This sensitive photodetector is also well-suited for applications in photoplethysmography (PPG), effectively detecting pulse signals in the NIR spectrum which has significant potential in medical diagnostics. This work advances the integration of cost-effective, wavelength-selective spectroscopic visible-NIR OPDs, paving the way for the next generation of sensitive photodetectors.

To ensure the growth of high-quality semiconductor-grade Czochralski (Cz) silicon, it is crucial to control the oxygen concentration within a specified range tailored to different device applications. This study presents a twodimensional, axisymmetric global model for heat and mass transfer during the growth of 300 mm semiconductor-grade Cz silicon crystals, based on the quasi-steady-state assumption. Intuitive distributions of oxygen concentration in both the melt and the crystal are illustrated at various solidification fractions. Simulation results are compared with our experimental results and those reported in literatures. Additionally, v/G distribution in the crystal is presented according to Voronkov's theory. Furthermore, the effects of turbulence models on the oxygen distribution and v/G distribution are investigated. The results reveal that the k-omega turbulence model predicts a lower oxygen concentration compared to the k-epsilon model, and there is no significant difference in the v/G distributions.

Mixed-halide perovskites (MHPs) have emerged as important semiconductor materials for optoelectronic devices due to the bandgap tunability by halide composition. However, their device applications are hampered by light-induced ion migration and halide segregation, leading to the formation of lower bandgap domains with red-shifted photoluminescence. Previous studies of phase segregation in MHPs have predominantly focused on their linear optical properties. Herein, nonlinear absorption (NLA) properties of MAPbBr2I films before and after femtosecond laser irradiation are investigated using the Micro-I-scan technique. An unusual NLA switching from reverse-saturable absorption (RSA) to saturable absorption (SA) under intense laser illumination is found. It is unveiled that the initial RSA originates from two-photon absorption in uniform bromide-rich regions of as-prepared film whereas the SA occurs due to state filling effect in the newly generated low bandgap I-rich phases under laser irradiation. The switching threshold and effective NLA coefficient are highly dependent on the distribution of halide ions, which is controllable through the laser illumination time. Furthermore, an all-optical logic gate scheme is demonstrated based on the unusual NLA switching. The results not only unveil that halide segregation results in NLA switching in MHPs but also pave the way for the realization of MHPs-based nonlinear photonic devices. An unusual nonlinear absorption (NLA) switching from reverse-saturable absorption (RSA) to saturable absorption (SA) is observed under the intense 800 nm femtosecond laser illumination. SA threshold and effective NLA coefficient are highly related to the distribution of halide ions modulated by different illumination times. An all-optical computing scheme based on photo-induced phase segregation is proposed. image

Perovskite solar cells are brought into sharp focus by their high-power conversion efficiencies and low costs. However, their photovoltaic performances are severely limited by the defects of perovskite films. In this study, we composed perovskite films with a two-step method and doped RbI into the precursor solution. The morphologies of perovskite films were measured with scanning electron microscope (SEM), ultraviolet visible absorption spectroscopy (UV-Vis), Xray diffraction (XRD) and photoluminescence spectroscopy (PL), and photovoltaic properties were determined with solar simulator. The effects of different RbI concentrations on film morphology and photovoltaic performance of the perovskite films were investigated in this work. Results show that doping with RbI of low-concentration is instrumental to the grain size and film morphology and enhances the absorbance of 400-580 nm spectrum. However, high-concentration doping is detrimental to the perovskite film, resulting in more holes on surface and diminished absorbance. The best doping concentration of RbI is 10 mg/mL. Comparing with undoped perovskite film, the grain size increased from 500-1000 nm to 1-2 μm, and short-circuit current density is increased from 23.48 mA/cm2 to 23.73 mA/cm2, with 10 mg/mL RbI doped into the precursor solution. This study not only helps optimize the perovskite film morphology, but also help improve photovoltaic performance of perovskite solar cells.

It remains challenging to fabricate high-efficiency all-inorganic perovskite solar cells (PSCs) at low temperature. Herein, the low-temperature preparation of high-efficiency CsPbI3 PSCs using hydroiodic acid (HI) and deionized water (H2O) as additives at synthetic temperature as low as 100 degrees C is proposed, which is beneficial for constructing even more complicated tandem or flexible solar cells. The additive of HI facilitates CsPbI3 to form a high-quality and smooth perovskite film at low temperature. The addition of an optimal amount of H2O further induces perovskite growth with larger grains and a smoother surface by the dissolution and recrystallization process in the grain boundary, which can suppress defects-induced nonradiative recombination. In this scenario, the corresponding device with structure of ITO/PEDOT:PSS/CsPbI3/PC61BM/Ag exhibits a high power conversion efficiency of 11.41% and the fill factor is increased from 62% to about 69%, compared with device based on CsPbI3 film without extra H2O treatment. The appropriate amount of H2O promotes the high-quality multigrain growth of the CsPbI3 film and reduces the internal defects, contributing to a significant improved charge collection efficiency. Therefore, this research work has paved a significant way to improving the quality of the all-inorganic perovskite film for highly efficient solar cells.

Herein, we develop a novel method to synthesize lanthanide-functionalized carbon quantum dots via free-radical copolymerization using the methyl methacrylate (MMA) monomer as a functional monomer and introducing a lanthanide complex to obtain the dual-emission fluorescent composite material FCQDs-Ln(TFA)3 (Ln = Eu, Tb; TFA: trifluoroacetylacetone). The obtained composites were fully characterized, and their structures were investigated by Fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Subsequently, a series of white-light-emitting polymer composite films FCQDs- (Eu:Tb)(TFA)3/poly(methyl methacrylate) (PMMA) were designed and synthesized by adjusting the ratio of Eu(TFA)3/Tb(TFA)3 under different wavelengths. More significantly, FCQDs-Tb(TFA)3 was selected as a sensitive probe for sensing metal cations due to excellent photoluminescence properties, revealing a unique capability of FCQDs-Tb(TFA)3 of detecting Fe(III) cations with high efficiency and selectivity. Furthermore, the sensing experiment results indicated that FCQDs-Tb(TFA)3 is ideal as a fluorescent nanoprobe for Fe3+ ion detection, and the lowest detection limit for Fe3+ is 0.158 μM, which is superior to many other previous related research studies. This pioneering work provides a new idea and method for constructing a dual-emission ratio sensor based on carbon quantum dots and also extends the potential application in the biological and environmental fields.

Abstract Organic-inorganic hybrid perovskites have emerged as promising emitters with the benefits of low cost and high color purity, but their low luminescence efficiency is a drawback for practical application on light emitting devices. Here we show that by incorporating proper amount of graphene quantum dots (GQDs) into perovskite precursor, dense CH3NH3PbBr3 films with reduced grain size and well passivated grain boundaries could be obtained. This gives rise to enhanced emission from GQD modified perovskite films. Our work thus provides a viable way to prepare highly luminescent perovskite films for optoelectronic applications.

The doping of semiconductor nanocrystals (NCs) is crucial for the optimization of the performance of devices based on them. In contrast to recent progress on the doping of compound semiconductor NCs and silicon NCs, the doping of germanium (Ge) NCs has lagged behind. Here it is shown that Ge NCs can be doped with phosphorus (P) during synthesis by a nonthermal plasma. It is found that there are more P atoms in the NC near‐surface region than in the NC core. P doping modifies the surface state of Ge NCs. Compressive strain can be incuced in Ge NCs by P which can explain the P‐doping‐enhanced oxidation resistance of Ge NCs. Stable dispersions of P‐doped Ge NCs in acetonitrile can be cast to produce films for field‐effect transistors (FETs). FET analysis shows that the electrical conductivity and electron mobility of a Ge‐NC film increase with the increase of the P doping level, although the electrical activation efficiency of P in the Ge‐NC film is low. Finally, atomic layer deposition of aluminum oxide at the surface of P‐doped Ge NCs is shown to improve the performance of the FETs.

In this work we introduce recently developed silicon-paste-enabled p-type doping for silicon. Boron-doped silicon nanoparticles are synthesized by a plasma approach. They are then dispersed in solvents to form silicon paste. Silicon paste is screen-printed at the surface of silicon wafers. By annealing, boron atoms in silicon paste diffuse into silicon wafers. Chemical analysis is employed to obtain the concentrations of boron in silicon nanoparticles. The successful doping of silicon wafers with boron is evidenced by secondary ion mass spectroscopy (SIMS) and sheet resistance measurements.