Time-resolved Photoluminescence Decay Research Articles

Control of Hybrid Exciton Lifetime in MoSe2/WS2 Moiré Heterostructures.

Hybrid excitons, characterized by their strong oscillation strength and long lifetimes, hold great potential as information carriers in semiconductors. They offer promising applications in exciton-based devices and circuits. MoSe2/WS2 heterostructures represent an ideal platform for studying hybrid excitons, but how to regulate the exciton lifetime has not yet been explored. In this study, layer hybridization is modulated by applying electric fields parallel or antiparallel to the dipole moment, enabling us to regulate the exciton lifetime from 1.36 to 4.60ns. Furthermore, the time-resolved photoluminescence decay traces are measured at different excitation power. A hybrid exciton annihilation rate of 8.9 × 10-4cm2s-1 is obtained by fitting. This work reveals the effects of electric fields and excitation power on the lifetime of hybrid excitons in MoSe2/WS2 1.5° moiré heterostructures, which play important roles in high photoluminescence quantum yield optoelectronic devices based on transition-metal dichalcogenides heterostructures.

Analysis of defects dominating carrier recombination in CeO2 single crystal for photocatalytic applications

In photocatalytic water splitting and CO2 reduction, recently, cerium oxide (CeO2) has been widely investigated. Defects that can directly dominate carrier recombination are essential for the photocatalytic performance of CeO2. In this study, several photoluminescence (PL) peaks are observed on the (100) face of an undoped CeO2 single crystal, indicating the presence of defects. Moreover, we characterize carrier recombination using time-resolved photoluminescence (TR-PL) and microwave photoconductivity decay (μ-PCD) measurements. The temperature dependence of decay curves is the result of carrier trapping and emission at deep levels. These decay curves are observed separately using a 565 nm band-pass filter (BPF) based on the PL spectra. The trap energy level ( ET ) and majority carrier capture cross-section ( σT ) of each defect are also analyzed using rate equations to fit the experimental results. The temperature-dependent time constants are well reproduced by a recombination model using hole traps HTinfrared and HTvisible at ET of 0.76 and 0.55 eV from the conduction or valence band, with estimated σT of the order of 10−21 and 10−22 cm2 for without and with the BPF, respectively. These findings regarding the presence of multiple defects in a single crystal indicate the necessity to focus on defect control.

Luminescent properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, and Ba)

We investigated the luminescence properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, or Ba) phosphors synthesized using the coprecipitation method. Structural analysis of the phosphors was performed using X-ray diffraction patterns, which revealed that the prepared samples exhibited a pure phase with diffraction peaks matching those of undoped orthorhombic structures. The luminescence properties of the phosphors were examined by measuring photoluminescence and photoluminescence excitation spectra. We found that both Eu2+ and Eu3+ emissions were detected for A = Ba and Ca, whereas only Eu2+ emission was observed for A = Sr. Further, time-resolved photoluminescence decay curves indicate the presence of Eu2+ and Eu3+ luminescence with different lifetimes. The optically stimulated luminescence (OSL) and thermoluminescence (TL) responses of the samples were investigated. The OSL and TL responses were found to vary linearly with the irradiation dose. This study sheds light on the potential applications of Eu-ion-doped ASO4 phosphors in radiation dosimetry and optoelectronic devices.

Ag-CsPbI3 nanocomposite structure in glasses boosts photoluminescence for efficient light emitting diodes

Nanocomposite structures based on perovskite nanocrystals (NCs) and metal nanostructures within transparent monolithic media hold promise for a wide range of applications in optoelectronics. However, the microstructure of such nanocomposites and the reason for enhanced emissions remain incompletely understood. In this work, we present the successful creation of Ag-CsPbI3 nanocomposite within a highly transparent borosilicate glass (Ag-CsPbI3 NCs@glass). We reveal that Ag and CsPbI3 NCs form after thermal treatment of the glass, either in the form of Ag-CsPbI3 heterostructures or of separate Ag and CsPbI3 NCs. Based on combined characterization of Mott-Schottky and steady-state photoluminescence (PL) of the products, we attribute the enhanced PL in the nanocomposite of Ag-CsPbI3 to the regulation of CsPbI3 lattice by Ag ions and/or the plasmonic effect of Ag NCs. Temperature-dependent time-resolved PL decay measurements suggest that Ag NCs could play an important role in the relaxation process of excited carriers by increasing the radiative recombination. Moreover, the Ag-CsPbI3 nanocomposite structure within the glass matrix curtails PL quenching caused by water molecules and high temperature. Using the Ag-CsPbI3 nanocomposite, we achieve high-performance white light-emitting diodes with a color rendering index of 83.9 and luminous efficiency of 58.07 lmW−1. This work elucidates the underlying mechanism on the enhanced PL in nanocomposites containing perovskite NCs and metal nanostructures, and aids in the rational design of glass-based perovskite nanocomposites for a diversity of optoelectronic applications.

Passivation of defective states in single crystal MAPbBr3 and their optoelectronic properties study

We fabricated high-quality Methylpropyl lead bromide (MAPbBr3) single crystals (SC) by introducing moderate amount electron-rich amino-terminated polyoxypropylene (PEA) additives via inverse temperature crystallization (ITC) method. The intramolecular vibrations and defective states of prepared MAPbBr3 single crystals were systemically studied by the in situ variable-temperature Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), the synchrotron-based X-ray absorption near edge structure (XANES) et al. We find the proper amount PEA additives would prevent the formation of intermediate states and crystal boundaries, passivating the density of defective states. The X-ray detection properties of single-crystal MAPbBr3 crystals were investigated, using both high dose and low dose X-ray photons at 40 keV in synchrotron beamlines. The photocurrent of optimized PEA-treated MAPbBr3 single crystals demonstrate better performance compared with the as-prepared single crystals. Meanwhile, the decay time of MAPbBr3 single crystal is decreased from 376 ns to 17.1 ns by Time-resolved photoluminescence (TRPL) decay measurement, owing to the defect passivation by 0.5 wt% PEA additives. The PEA-treated single crystals possess much faster decay time than the commercialized Cerium-doped Yttrium Aluminum Garnet (Ce:YAG) scintillator (∼100ns). These results help elucidate the passivation of defective states and contribute paths to manufacture high-quality single crystal perovskites for next-generation optoelectronic devices.

(Poster Award - 2nd Place) Layer-Number Engineered Momentum-Indirect Interlayer Excitons with Large Spectral Tunability

The diversity of two-dimensional (2D) materials provides van der Waals heterostructures with abundant degrees of freedom and makes the family a promising candidate to realize novel optoelectronic devices and an attractive platform for exploring physical phenomena. Interlayer excitons in type-II van der Waals heterostructures are equipped with an oriented permanent dipole moment and long lifetime and thus would allow promising applications in excitonic and optoelectronic devices. However, in the widely studied van der Waals heterostructures constructed by transition metal dichalcogenides, the formation of interlayer excitons is limited by the lattice mismatch, rotational and translational alignment between the constituent layers, increasing the complexity of the device fabrication. Here, I will report on the robust momentum-indirect interlayer exciton emission with widely tunable emission energy via layer engineering in transition metal dichalcogenide/2D perovskite heterostructures. The transition metal dichalcogenides with different thicknesses and 2D perovskites with different layer numbers of the inorganic octahedral slabs are stacked to form type-II van der Waals heterostructures without considering special orientation arrangement and momentum mismatch. The presence of interlayer excitons is supported by the excitation-power- and temperature-dependent photoluminescence studies, photoluminescence excitation spectroscopy, time-resolved photoluminescence decay studies and electric field-dependent photoluminescence studies. Taking advantage of the thickness- or layer-number-dependence of the electronic band structure of the constituent materials, the emission energy of the interlayer excitons in our heterostructures can be tuned from 1.3 eV to 1.6 eV, providing strong evidence for the applications of van der Waals interface engineering to broad-spectrum optoelectronics. In addition, the diffusion coefficient of interlayer excitons in our heterostructures can be estimated to be ~10 cm2 s−1, which is at least one order of magnitude larger than that in the van der Waals heterostructures with Moiré superlattice, suggesting a non-localized nature that would be beneficial to the excitonic devices. Our study would offer new insights into the nature of interlayer excitons and provoke further research into their dynamics.

Study of time-resolved photoluminescence decay curves in Al-doped ZnO and Eu-doped Cd1−xZnxS nanophosphors

Study of time-resolved photoluminescence decay curves in Al-doped ZnO and Eu-doped Cd1−xZnxS nanophosphors

Time-resolved photoluminescence analysis of ceramic Ce:GAGG scintillators.

This paper introduces the characteristics and efficiency of post-treatment methods for enhancing the timing resolution of ceramic Ce:GAGG scintillators. The thermal annealing and surface treatments were included to analyze their impact on time-resolved photoluminescence (TRPL) and thermoluminescence (TL) characteristics. Optical properties were improved by suppressing nonradiative recombination due to the reduced surface defects, while heat-treatment removes traps as confirmed by TL measurements. TRPL decay characteristics revealed that samples treated with mechanical polishing followed by heat treatment exhibited the best scintillation performance, with a slow component of 272.3 ns. These findings will aid in developing techniques for improving the luminescence of other inorganic scintillators.

Electrochemical control of surface passivation and deformation in InP nanotetrapods

In this study, we investigate the influence of electrochemical doping on the optical properties of single-crystalline InP nanotetrapods. Our focus is on examining the variations in photoluminescence (PL) intensity exhibited by these InP tetrapods in response to applied electrical potential. We observe that the PL intensity undergoes significant changes depending on the nature of the charge transfer occurring during electrochemical doping. Specifically, electron transfer from the electrode to the InP tetrapods leads to a noticeable quenching of the PL intensity, which can be attributed to the removal of surface ligands. However, when additional holes are injected, we observe a remarkable increase in the PL intensity exceeding 60%. Through an analysis of steady-state PL spectra and time-resolved PL decay dynamics, we propose that the injected holes occupy surface hole trap states, resulting in surface passivation and thus enhancing the PL intensity. Our findings highlight the potential of these InP nanotetrapods as a novel nanostructure for future advancements in nanocrystal applications. By elucidating the impact of electrochemical doping on the optical properties of these materials, we contribute to the understanding and exploration of their potential applications in optoelectronic devices and related fields.

Ultrafast Study of Excited State Dynamics of Amino Metal Halide Molecular Clusters.

The excited state dynamics of ligand-passivated PbBr2 molecular clusters (MCs) in solution have been investigated for the first time using femtosecond transient absorption spectroscopy. The results uncover a transient bleach (TB) feature peaked around 404 nm, matching the ground state electronic absorption band peaked at 404 nm. The TB recovery signal can be fitted with a triple exponential with fast (10 ps), medium (350 ps), and long (1.8 ns) time constants. The medium and long time constants are very similar to those observed in the time-resolved photoluminescence (TRPL) decay monitored at 412 nm. The TB fast component is attributed to vibrational relaxation in the excited electronic state while the medium component with dominant amplitude is attributed to recombination between the relaxed electron and hole. The small amplitude slow component is assigned to electrons in a relatively long-lived excited electronic state, e.g., triplet state, or shallow trap state due to defects. This study provides new insights into the excited state dynamics of metal halide MCs.

Highly Efficient HTM-Free Tin Perovskite Solar Cells with Outstanding Stability Exceeding 10000 h.

The bottleneck in the rapid development of tin-based perovskite solar cells (TPSCs) is the inherent chemical instability. Although this is being addressed continuously, the device performance has not improved further due to the use of PEDOT:PSS as the hole-transport material (HTM), which has poor long-term stability. Herein we have applied commercial ITO nanoparticles over ITO glass substrates and altered the surface chemistry of the ITO electrode via a simple two-step thermal annealing, followed by a UV-ozone treatment. These surface-modified ITO electrodes display promising interfacial characteristics, such as a suitable band alignment owing to significantly reduced surface carbon contamination, increased In-O bonding, and reduced oxygen vacancies, that enabled fabrication of an HTM-free TPSC device according to a two-step method. The fabricated device possessed an outstanding power conversion efficiency (PCE) of 9.7%, along with a superior long-term stability by retaining over 90% of the initial PCE upon shelf storage in a glovebox for a period of over 10000 h. The application of ITO nanoparticles led to effective interfacial passivation, whose impacts on the long-term durability were assessed using electrochemical impedance spectroscopy, time-resolved photoluminescence decay profiles, and femtosecond transient absorption spectroscopy techniques.

A PET and ESIPT-communicated ratiometric, turn-on chromo-fluorogenic sensor for rapid and sensitive detection of sarin gas mimic, diethylchlorophosphate

Fast and precise identification of toxic G-series nerve agents in the solution and vapor phase is urgently needed to save human beings from unwanted wars and terrorist attacks, which is challenging to execute practically. In this article, we have designed and synthesized a sensitive and selective phthalimide-based chromo-fluorogenic sensor, DHAI, by a simple condensation process that shows ratiometric and turns on chromo-fluorogenic behavior towards Sarin gas mimic diethylchlorophosphate (DCP) in liquid and vapor phases, respectively. A colorimetric change, from yellow to colorless, is observed in the DHAI solution due to the introduction of DCP in daylight. A remarkable cyan color photoluminescence enhancement is noticed in the presence of DCP in the DHAI solution, which is observable to the naked under a portable 365nm UV lamp. The mechanistic aspects of the detection of DCP by employing DHAI have been revealed by time-resolved photoluminescence decay analysis and 1H NMR titration investigation. Our probe DHAI exhibits linear photoluminescence enhancement from 0 to 500μM with a detection limit of nanomolar range from non-aqueous to semi-aqueous media. For practical utility, a DHAI-stained test kit employing Whatman-41 filter paper has been fabricated and used as a portable and displayable photonic device for on-site detection of Sarin gas surrogate, DCP. Also, a dip-stick experiment has been demonstrated to identify the vapor of Sarin gas mimics DCP colorimetrically and fluorometrically. The concentrations of DCP in various water samples have been evaluated with the help of a standard fluorescence curve for real sample analysis.

Stability of self-encapsulated CsPbX3@PbX(OH)(X=Cl,Br) perovskite quantum dots in polar solvents

Inorganic halide perovskite quantum dots has excellent optical and photoelectric properties, so it has great potential in photovoltaic, photoelectric devices, display lighting, medical detection and other fields. However, its commercial application is hampered by its instability. In this paper, the perovskite quantum dots encapsulated by PbX (OH)(X = Cl,Br) can obtain hexahedral CsPbBr3@PbBr(OH), cube CsPbCl3@PbCl(OH) and spindle CsPbCl3@PbBr(OH) between hexahedron and cube. The core-shell encapsulation and interchange combination are realized. Before and after encapsulation, the color coordinates of CsPbX3 (X = Cl,Br) perovskite quantum dots basically did not change, no other crystal phases were found in the XRD lines, which indicatied that the PbX (OH) (X = Cl,Br) encapsulation layer did not change the crystal structure of perovskite quantum dots. PbX (OH) (X = Cl,Br) encapsulation layer plays the role of water-blocking layer and protective layer, which greatly improves the stability of CsPbX3 (X = Cl,Br) perovskite quantum dots in polar solvents. After encapsulation, the photoluminescence quantum yield (PLQY) and time-resolved photoluminescence decay performance of CsPbX3 (X = Cl,Br) perovskite quantum dots are greatly improved. The surface passivation and trap density of perovskite nanocrystals can be reduced by PbX (OH) (X = Cl,Br) wrapping, which extends the fluorescence life of CsPbX3 (X = Cl,Br) and improving the PL stability of perovskite structure. Room temperature (RT) crystallization method does not require inert gas protection, high temperature and high pressure conditions. It also has good repeatability, which provides a better alternative to hot injection. Meanwhile, the improvement of package stability provides a broader prospect for the application and promotion of lead halide perovskite.

Methylammonium Cation-Regulated Controllable Preparation of CsPbBr3 Perovskite Quantum Dots in Polystyrene Fiber with Enhanced Water and UV Light Stabilities

In situ fabrication of lead halide perovskite quantum dots (PQDs) is important for narrow-band emitters for LED displays due to the simple work procedure and convenient usability; however, the growth of PQDs is not readily controllable in the preparation, resulting in low quantum efficiency and environmental instability of PQDs. Here, we demonstrate an effective strategy to controllably prepare CsPbBr3 PQDs in polystyrene (PS) under the regulation of methylammonium bromide (MABr) via electrostatic spinning and thermal annealing techniques. MA+ slowed down the growth of CsPbBr3 PQDs and acted as a surface defect passivation reagent, which was proved by Gibbs free energy simulation, static fluorescence spectra, transmission electron microscopy, and time-resolved photoluminescence (PL) decay spectra. Among a series of prepared Cs1-xMAxPbBr3@PS (0 ≤ x ≤ 0.2) nanofibers, Cs0.88MA0.12PbBr3@PS shows the regular particle morphology of CsPbBr3 PQDs and the highest photoluminescence quantum yield of up to 39.54%. The PL intensity of Cs0.88MA0.12PbBr3@PS is 90% of the initial intensity after immersing in water for 45 days and 49% of the initial value after persistent ultraviolet (UV) irradiation for 27 days. A high color gamut containing 127% of the National Television Systems Committee standard with long-time working stability was also obtained on light-emitting diode package measurements. These results demonstrate that MA+ can effectively control the morphology, humidity, and optical stability of CsPbBr3 PQDs in the PS matrix.

Cost-efficient single photon-sensitive nanosecond gated spectrometer based on commercial grade image intensifier

A commercial grade low-cost image intensifier was modified with a fast transistor gating circuit for time-resolved photoluminescence spectra and decay measurements. Gating exposure of 20 ns and spectral sensitivity in the 300–1000 nm range were achieved. Operation frequency in 5 Hz to 0.3 MHz range was verified by a pulsed laser diode. Pulsed repetitive image detection was integrated on a cooled CMOS camera. High dynamic range and wide spectral resolution were achieved. The thermal noise, reduced by three orders of magnitude at -16°C cooling and a high gain of 104, allowed single photon detection. Application of the spectrometer for sensitive photoluminescence decay measurements at pulsed laser excitation was performed on MAPbBr3 perovskite and CsI(Tl) scintillator crystals. The decay lifetimes of 400–600 ns and 100–6000 ns were determined, respectively. CsI(Tl) scintillator showed much stronger x-ray luminescence intensity due to larger defect density.

Graphene/III–V Quantum Dot Mixed-Dimensional Heterostructure for Enhanced Radiative Recombinations via Hole Carrier Transfer

Fabrication of high quantum efficiency nanoscale device is challenging due to increased carrier loss at surface. Low dimensional materials such 0D quantum dots and 2D materials have been widely studied to mitigate the loss. Here, we demonstrate a strong photoluminescence enhancement from graphene/III-V quantum dot mixed-dimensional heterostructures. The distance between graphene and quantum dots in the 2D/0D hybrid structure determines the degree of radiative carrier recombination enhancement from 80% to 800% compared to the quantum dot only structure. Time-resolved photoluminescence decay also shows increased carrier lifetimes when the distance decreases from 50 to 10 nm. We propose that the optical enhancement is due to energy band bending and hole carrier transfer, which repair the imbalance of electron and hole carrier densities in quantum dots. This 2D graphene/0D quantum dot heterostructure shows promise for high performance nanoscale optoelectronic devices.

The role of boron related defects in limiting charge carrier lifetime in 4H–SiC epitaxial layers

One of the main challenges in realizing 4H–SiC (silicon carbide)-based bipolar devices is the improvement of minority carrier lifetime in as-grown epitaxial layers. Although Z1/2 has been identified as the dominant carrier lifetime limiting defect, we report on B-related centers being another dominant source of recombination and acting as lifetime limiting defects in 4H–SiC epitaxial layers. Combining time-resolved photoluminescence (TRPL) measurement in near band edge emission and 530 nm, deep level transient spectroscopy, and minority carrier transient spectroscopy (MCTS), it was found that B related deep levels in the lower half of the bandgap are responsible for killing the minority carriers in n-type, 4H–SiC epitaxial layers when the concentration of Z1/2 is already low. The impact of these centers on the charge carrier dynamics is investigated by correlating the MCTS results with temperature-dependent TRPL decay measurements. It is shown that the influence of shallow B acceptors on the minority carrier lifetime becomes neutralized at temperatures above ∼422 K. Instead, the deep B related acceptor level, known as the D-center, remains active until temperatures above ∼570 K. Moreover, a correlation between the deep level concentrations, minority carrier lifetimes, and growth parameters indicates that intentional nitrogen doping hinders the formation of deep B acceptor levels. Furthermore, tuning growth parameters, including growth temperature and C/Si ratio, is shown to be crucial for improving the minority carrier lifetime in as-grown 4H–SiC epitaxial layers.

Insight into Hot Carrier Kinetics of CsPbBr3/ZnO Heterostructures for Photodetector Application

Understanding the hot carrier kinetics in heterostructures of inorganic halide perovskite nanocrystals (PNCs) and extraction of the excess energy of hot-carriers is crucial for their future emergence in optoelectronic devices. Herein, CsPbBr3/ZnO heterostructures have been prepared via the most adopted in situ hot-injection method, and ZnO nanoparticles were obtained by a simple chemical process. We have investigated the carrier transfer dynamics through steady-state and ultrafast optical measurements. Steady-state measurements (i.e., photoluminescence and time-resolved photoluminescence decay) reveal that electron transfer from PNCs to surface-attached ZnO nanoparticles is the most probable transition process that happened in heterostructured systems. Furthermore, deep insights into the charge transfer kinetics were investigated by performing ultrafast transient absorption (UTA) spectroscopy at two varying pump fluences (i.e., 0.40 and 0.20 mW) with an excitation wavelength of 450 nm. UTA analysis reveals a significant slow hot carrier cooling at 0.40 mW fluence (from 670 fs to 1.56 ps) and 0.20 mW (from 480 fs to 1.23 ps) in CsPbBr3/ZnO heterostructure systems, suggesting reduced exciton recombination and high charge-carrier transfer through the heterostructure interface. The efficient charge extraction in CsPbBr3/ZnO results in a measurable change in photodetector responsivity and detectivity. This study provides an understanding of the hot carrier kinetics of metal halide perovskites CsPbBr3/ZnO for optoelectronic device applications.

Improved Crystallization of Lead Halide Perovskite in Two-Step Growth Method by Polymer-Assisted "Slow-Release Effect".

Fast reaction between organic salt and lead iodide always leads to small perovskite crystallites and concentrated defects. Here, polyacrylic acid is blended with organic salt, so as to regulate the crystallization in a two-step growth method. It is observed that addition of polyacrylic acid retards aggregation and crystallization behavior of the organic salt, and slows down the reaction rate between organic salt and PbI2 , by which "slow-release effect" is defined. Such effect improves crystallization of perovskite. X-ray diffraction study shows that, after addition of 2mm polyacrylic acid, average crystallite size of perovskite increases from ≈40 to ≈90nm, meanwhile, grain size increases. Thermal admittance spectroscopy study shows that trap density is reduced by nearly one order (especially for deep energy levels). Due to the improved crystallization and reduced trap density, charge recombination is obviously reduced, while lifetime of charge carriers in perovskite film and devices are prolonged, according to time-resolved photoluminescence and transient photo-voltage decay curve tests, respectively. Accordingly, power conversion efficiency of the device is promoted from 19.96 (±0.41)% to 21.84 (±0.25)% (with a champion efficiency of 22.31%), and further elevated to 24.19% after surface modification by octylammonium iodide.

Photoluminescence and lifetime studies of C-dot decorated CdS/ZnFe2O4 composite designed for photoelectrochemical applications

Cadmium sulphide (CdS) is a well-known material for photoelectrochemical water splitting as a photoanode. The valence and conduction band edges are well suited for both hydrogen and oxygen evolution reactions. However, a major drawback in the case of cadmium sulphide is its photocorrosion. In this regard, formation of a Type II heterostructure helps in well separation of the photogenerated charge carriers and reduces photocorrosion. Herein, we have incorporated a carbon dot layer (high conductivity) in between a CdS/ZnFe2O4 Type II composite heterostructure to further enhance the photoelectrochemical performance of the material. Steady state photoluminescence (PL) study revealed that maximum PL intensity is observed in the case of bare CdS while minimum intensity in the case of ternary composite after the incorporation of carbon dots. The inflation of PL intensity revealed the overall increase in the conductivity and enhanced charge separation at the interface after composite formation. The time-resolved photoluminescence (TRPL) decay dynamics have also been studied. The lifetime of the charge carriers for the ternary composite was found to be 2.41 ns, which is much higher than the bare (0.78 ns) and binary composite (0.85 ns), indicating the improved charge separation and the stability after composite formation (CdS/C-dot/ZnFe2O4). This further aids in the enhancement of photocurrent generation. The photocurrent density is enhanced by approximately 50 times compared to the bare material (CdS) and 5 times compared to the binary composite (CdS/ZnFe2O4).