Electron-hole Research Articles

Tuning the photovoltaic potential of thiazole based materials via incorporation of selenophene and electron acceptors rings at peripheral positions: A DFT approach

The non-fullerene acceptor (NFA) chromophores have sparked scientific and economic interest, due to their rapid advancements in power conversion efficiencies. Therefore, a series of new chlorothiazole based compounds (STM1-STM6) with A1–π–A2–π–A1 configuration was designed using reference chromophore (STMR). Structural modifications were made via incorporating selenophene and extended acceptor units, to enhance photovoltaic response in the designed materials. Density functional theory/time dependent-density functional theory (DFT/TD-DFT) calculations were executed at M06/6-311G (d,p) level to investigate key electronic and photovoltaic properties of STM1-STM6. So, various analyses such as UV–Visible, frontier molecular orbitals (FMOs), transition density matrix (TDM), density of states (DOS), open circuit voltage (Voc) and binding energy (Eb) were conducted to comprehend the photovoltaic properties. The designing in structural aspects with terminal acceptors and π-linker induced a reduction in energy gaps (ΔE = 2.078–2.237 eV) with an enhancement in the bathochromic shift (λmax = 744.650–798.250 nm in chloroform) than reference compound. A higher exciton dissociation rate was observed in all the compounds due to lower binding energy values (Eb = 0.525–0.572 eV). Additionally, TDM and DOS findings further endorsed the effective charge delocalization from HOMO to LUMO. Among all the examined compounds, STM3 exhibited the smallest band gap (2.078 eV), highest absorption maxima (798.250 nm), and the lowest exciton binding energy (0.525 eV), indicating significant electronic properties. Moreover, Voc analysis was conducted with respect to HOMOPBDBT-LUMOacceptor for all the designed chromophores; consequently, STM2 demonstrated a substantial Voc value of 1.647 V. Similarly, electron hole analysis was also conducted and significant electron and hole density was observed in all the investigated compounds, especially in STM2. The entitled compounds with photovoltaic potential would be considered as promising materials for the development of solar energy devices.

Bulk photovoltaic effect in Cu-doped LiNbO3 single crystals with controlled oxidation state

We investigate the bulk photovoltaic (PV) effect of Cu-doped LiNbO3 single crystals with various oxidation states of Cu. The Cu-doped samples exhibit the PV response under below-bandgap excitation, and the onset of photocurrent shifts depending on partial oxygen pressures (pO2) during the annealing treatment. Open-circuit voltages (V oc) under simulated sunlight (AM 1.5 G) illumination are changed by pO2, and crystals annealed at pO2 = 1.0 × 10−10 atm exhibit the highest V oc of 1700 V. Moreover, density functional theory (DFT) calculations for Cu-doped LiNbO3 cells with Cu2+ on the Li site and the Nb site indicate that half-filled gap states derived from 3d orbitals of Cu are formed within the bandgap. Based on Glass coefficients obtained by the analyses of polarization angle-dependent photocurrent densities and the DFT calculations, we consider that Cu2+ on the Li site is the major active site for the generation and separation of electron–hole pairs under visible light at hν = 2.4 eV.

Visible‐light‐driven selective aerobic oxidation of olefins over bifunctional photocatalyst Cu‐BTC‐TiO2 in water

Metal organic frameworks (MOFs) as semiconductor‐like materials, are considered to be promising photocatalysts for heterogeneous phtotocatalytic oxidation of styrene. Herein, copper‐based MOFs and titanium dioxide composite bifunctional photocatalyst (Cu–benzene‐1,3,5‐tricarboxylate‐titanium dioxide, Cu‐BTC‐TiO2) wereas synthesized, and the selective oxidation of styrene was achieved under mild conditions of oxygen and water. Cu‐BTC‐TiO2 nanoparticles (NPs) exhibited more than three times higher styrene conversion than Cu‐BTC and TiO2 individually under same condition, and the desired product benzaldehyde can be obtained with up to 82% yield. The improved performance may be attributed to the acid site of Cu‐BTC, which is conducive to the adsorption and activation of styrene. In addition, the formation of heterojunction between Cu‐BTC and TiO2 can regulate the band gap of photocatalyst, which is favorable for light absorption, and facilitate the separation, transportation and utilization of photogenerated electron holes. The present protocol features good functional group tolerance, mild reaction conditions, and the reusability of catalyst.

An EPR study of point defects in zinc oxide thin films

We studied ZnO thin films deposited on glass slides by thermal evaporation in vacuum followed by heat treatment in open air or Ar flow. The samples were characterized using x-ray diffraction, Raman scattering, photoluminescence (PL), and electron paramagnetic resonance (EPR) spectroscopy. We observed a broad PL band in the visible region at spectral positions of 504 and 560 nm and a low-intensity band in the UV region at 390 nm. The EPR spectra display a clear first derivative structure at g=1.96 at temperatures below 200 K. The PL spectrum shows red-shifted valence to conduction band emission due to electron hole recombination through shallow surface states. We found an activation energy of E a = 4.2 meV using the Arrhenius plot and estimated concentrations of paramagnetic defects and spin–spin relaxation time constants of 1016 m−3 and 10–14 s, respectively.

Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

ZnO/layered carbon nanocomposites with varied sizes of ZnO nanoparticles (NPs) were synthesized by mechanical milling of mixture of ZnO NPs and carbon NPs. The NP size of ZnO was controlled with average particle sizes about 19.33, 21.87, 24.21, and 27.89 nm by varying the concentrations of carbon NPs viz 0, 2, 5, and 10 weight percent, respectively, in the mixture. Presence of carbon with ZnO in the form of composite also resulted in the enhanced shift of the band gap of ZnO due to the optical transitions in the impurity states or presence of carbon as compared to the ZnO size change alone. Additionally, the enhancement of absorbance in the visible region with an increase in carbon content was observed. Such an increase in absorbance can enhance the photocatalytic activity of ZnO NPs. Raman bands for ZnO NPs also were found to shift faster in the presence of layered carbon. The quenching of visible photoluminescence emission of ZnO NPs with an increase in concentration of carbon NPs in the composite indicated the phenomenon associated with transfer of electrons from ZnO to layered carbon helping the separation of photo-generated electrons and holes in ZnO and can lead to enhancement of the photocatalytic activity of ZnO NPs. In the photocatalytic studies, it was observed that the degradation of methylene blue (MB) dye was significantly enhanced by the increase of content of layered carbon in the nanocomposite. The sample containing 10% carbon showed the highest adsorption in dark conditions which was up to 60% of the starting strength and this was further enhanced to 88% in the presence of UV radiation. Enhanced adsorption of MB dye and the effective separation of electron–hole pairs due to charge transfer were believed to be the main causes behind such kind of improvement in the photocatalytic effects.

Oxalic Acid-Assisted Photo-Fenton Catalysis Using Magnetic Fe3O4 Nanoparticles for Complete Removal of Textile Dye

Textile industry effluents contain several hazardous substances, such as dye-containing effluents, which pose environmental and aesthetic challenges. Presently, the microbial-based remediation process is in use. This study investigated the application of ferrous–ferric oxide (Fe3O4) nanoparticles, a readily formulated nanoadsorbent, to remove scattered dye molecules from industrial effluents. The ferrous–ferric oxide nanoparticles were prepared using a chemical co-precipitation method. The nanoparticles had 26.93 emu g−1 magnetization, with sizes smaller than 20 nm, and possessed a highly purified cubic spinel crystallite structure. The catalytic activity of the iron oxide depended on the dose, photocatalytic enhancer, i.e., H2O2 level, pH of the reaction medium, and dye concentration. We optimized the Fenton-like reaction to work best using 1.0 g/L of ferrous–ferric oxide nanoparticles, 60 mM oxalic acid at pH 7.0, and 60 ppm of dye. Iron oxides act as photocatalysts, and oxalic acid generates electron–hole pairs. Consequently, higher amounts of super-radicals cause the rapid degradation of dye and pseudo-first-order reactions. Liquid chromatography–mass spectrometry (LC-MS) analysis revealed the ferrous–ferric oxide nanoparticles decolorized and destroyed Disperse Red 277 in 180 min under visible light. Hence, complete demineralization is observed using a photo-Fenton-like reaction within 3 h under visible light. These high-capacity, easy-to-separate next-generation adsorption systems are suggested to be suitable for industrial-scale use. Ferrous–ferric oxide nanoparticles with increased adsorption and magnetic properties could be utilized to clean environmental pollution.

Substituent effects in Benzo[c][1,2,5]thiadiazole-based donor–acceptor conjugated polymers: A density functional theory study

In the development of high-efficient organic photovoltaics (OPVs), theoretical screening methods for donor–acceptor conjugated polymers (D-A CPs) usually requires high experimental costs. In this study, we employed a time-dependent density functional theory, to investigate the electron–hole excitation characteristics of D-A CPs with substituent effects of methoxy (OCH3), fluorine (F) on the poly(4,7-bis(4′,5′-dimethyl-[2,2′-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole) (PBTD4T). Our findings revealed that the OCH3 substituent increases the highest occupied molecular orbital energy level, decreases the band gap, and enhances charge transfer and electron density in the D fragments. This approach highlights the potential of substituents for manipulating the electronic properties of CPs, offering a pathway for future development.

Reinforced Electrons Transfer and Capture in S‐Scheme TiO2@Co(OH)F‐Pt Heterojunction for Excellent Solar Hydrogen Evolution

AbstractTiO2 with the merits of non‐toxicity, high stability, strong redox capability, and low cost, has garnered considerable attention in the fields of renewable energy. However, the practical application is limited by the rapid recombination of photogenerated electron–hole pairs, posing a challenge to enhance electron utilization without compromising catalytic activity. Herein, S‐scheme TiO2@Co(OH)F‐Pt heterojunction through a simple hydrothermal and photo‐deposition method is constructed. The experimental tests and theoretical computation indicate that Co(OH)F possesses a smaller work function and a more negative conduction band (CB) position, significantly accelerating the separation of photogenerated charge carriers. Furthermore, the built‐in electric field, band bending between TiO2 and Co(OH)F, and the electron sink of Pt nanoparticles, facilitate the reduction of protons to hydrogen. The as‐prepared TiO2@Co(OH)F‐Pt exhibits high‐performance solar hydrogen evolution with an evolution rate of 1401 µmol h−1. The apparent quantum yield (AQY) is determined to be 22.8% at a single wavelength of 365 nm. After reacting 12 h for three cycles, no noticeable performance degradation occurs, showing good stability of the catalyst. This work provides a rational strategy for the design of heterojunction photocatalysts for driving the production of new energy and useful chemicals.

Nonvolatile photoelectric memristor for reconfigurable Boolean logic operation and data storage

Photoelectric memristors have the advantages of highly parallel computing and large-scale interconnection, which provides a promising method for reconfigurable logic operations and greatly promotes the development of new memory computing technology. In this paper, a photoelectric memristor was fabricated using natural gelatin and water-soluble CdSe/ZnS quantum dots with a shell structure. Under light stimulation, the device undergoes photoelectric effects in the dielectric layer, generating electron–hole pairs and causing the device to transition from a high-resistance state to a low-resistance state. Seven nonvolatile logic functions are achieved using three wavelengths of light excitation devices. Compared with traditional electrically controlled memristors, emerging photoelectric memristors are more attractive because they can integrate the advantages of photons and electrons.

ETL and HTL Engineering in CH3NH3PbBr3 Perovskite for Stable and Efficient Performance Photovoltaic Devices Applications using SCAPS‐ 1D

AbstractPerovskite solar cells are increasingly acknowledged for their unique characteristics. This study focuses on simulating the impact of methylammonium lead bromide‐based perovskites, as the absorber in perovskite solar cells using the SCAPS‐1D simulator. The research delves into how the performance of these solar cells is affected by the choice of Electron Transport Layers (TiO2, PCBM, SnO2, and ZnO) and Hole Transport Layer (Cu2O) with Ni and Al as the back and front contact. This investigation marks the first comprehensive exploration of CH3NH3PbBr3. The performance of these device architectures is significantly influenced by factors such as defect density, absorber thickness, ETL thickness, and the combination of different ETLs. The power conversion efficiencies of devices optimized with TiO2, PCBM, SnO2, and ZnO are found to be 15.46%, 15.33%, 15.01%, and 14.99%, respectively. Furthermore, this study elucidates the impact of absorber and HTL thickness. Also, they have discussed the VBO, CBO for different ETLs. Additionally, the effects of series resistance, shunt resistance are examined, operating temperature, quantum efficiency (QE), capacitance‐voltage characteristics, generation and recombination rates, current density‐voltage (J‐V), and impedance analysis of the devices. Through this extensive simulation study, researchers are equipped to develop cost‐effective and highly efficient PSCs, thereby advancing solar technology.

Nanoarchitectonics of bamboo-based heterojunction photocatalyst for effective removal of organic pollutants

A high-performance photocatalyst with both efficient and reusable performance is essentially demanded for the purification of organic wastewater and the removal of indoor formaldehyde. However, recovery of photocatalyst particles from the reaction system remains a challenge. Herein, based on the abundant pore structure of natural bamboo and the outstanding photocatalytic activity of ZnO/WO3, we fabricated an efficient bamboo-based photocatalyst (ZnO/WO3@bamboo) for the efficient photocatalytic degradation of formaldehyde and organic dyes. The pretreatment of bamboo substrates with NaOH solution resulted in the formation of nucleation sites for ZnO/WO3 growth within bamboo cellulose channels. Subsequently, the as-prepared ZnO and WO3 were mixed in different mass ratios, and loaded on the pretreated bamboo substrates using the hydrothermal method. The results showed that the ZnO/WO3@bamboo had the effective function of photocatalytic degradation of formaldehyde gas and organic dyes. Moreover, the as-prepared ZnO/WO3@bamboo photocatalyst demonstrated superior recycling ability toward organic pollutants, which was described by photocatalytic degradation efficiency of formaldehyde gas more than 89% after 10 cycles, and organic dyes over 93% after 20 cycles. The coupling of ZnO and WO3 leads to electron delocalization, which caused the electron holes generated in the valence band (VB) of ZnO to delocalize to the VB of WO3, and reduced the recombination of electron-hole. Therefore, the photocatalytic degradation performance of the ZnO/WO3@bamboo was enhanced. The proposed ZnO/WO3@bamboo photocatalyst holds great promise in the field of air pollution and wastewater remediation.

Enhanced optical properties of BiVO4 photoanode with subwavelength moth-eye structure fabricated via e-beam evaporation and direct printing

Photoelectrochemical (PEC) water splitting, which harnesses solar radiation (an infinite energy source) for clean hydrogen production without carbon-dioxide emissions, is an ideal eco-friendly energy technology. The core reactions in PEC water splitting, involving the oxidation and reduction of water, are driven by electron–hole pairs generated through solar energy absorption. Consequently, the light-absorption efficiency emerges as a critical parameter in PEC devices. Conventional thin-film-type photoanodes, however, grapple with limited absorption due to their high reflectance, hindering absorption and carrier separation efficiency. Conversely, moth-eye-structured photoanodes exhibit an anti-reflection effect stemming from their subwavelength structure, markedly enhancing light-absorption efficiency. In this study, we present the design and fabrication of a densely packed moth-eye-structured bismuth vanadate (BiVO4) (M-BVO) photoanode, which is engineered to possess superior light absorption properties. The photoanode was fabricated via direct printing, electron-beam evaporation, and Vanadium calcination processes. The light absorption of the resulting M-BVO photoanode increased to approximately 92 % within the 300–500 nm wavelength range, with the absorption efficiency (ηabs) surging to 82.9 %. This represents a 23.5 % enhancement compared to its flat BiVO4 counterparts. Impressively, the photocurrent density of M-BVO reached 2.98 mA cm−2 at 1.23 VRHE, 37.6 % higher than that of flat BiVO4. These results indicate that the PEC efficiency can be significantly increased through moth-eye structuring, emphasizing the indispensable role of nanostructure research in the manufacture of high-efficiency photoanodes.

Exploration and Optimization of the Polymer-Modified NiOx Hole Transport Layer for Fabricating Inverted Perovskite Solar Cells.

The recombination of charge carriers at the interface between carrier transport layers such as nickel oxide (NiOx) and the perovskite absorber has long been a challenge in perovskite solar cells (PSCs). To address this issue, we introduced a polymer additive poly(vinyl butyral) into NiOx and subjected it to high-temperature annealing to form a void-containing structure. The formation of voids is confirmed to increase light transmittance and surface area of NiOx, which is beneficial for light absorption and carrier separation within PSCs. Experimental results demonstrate that the incorporation of the polymer additive helped to enhance the hole conductivity and carrier extraction of NiOx with a higher Ni3+/Ni2+ ratio. This also optimized the energy levels of NiOx to match with the perovskite to raise the open-circuit voltage to 1.01 V. By incorporating an additional NiOx layer beneath the polymer-modified NiOx, the device efficiency was further increased as verified from the dark current measurement of devices.

Combined Charge Extraction by Linearly Increasing Voltage and Time-Resolved Microwave Conductivity to Reveal the Dynamic Charge Carrier Mobilities in Thin-Film Organic Solar Cells.

This article reports a purely experiment-based method to evaluate the time-dependent charge carrier mobilities in thin-film organic solar cells (OSCs) using simultaneous charge extraction by linearly increasing the voltage (CELIV) and time-resolved microwave conductivity (TRMC) measurements. This method enables the separate measurement of electron mobility (μe) and hole mobility (μh) in a metal-insulator-semiconductor (MIS) device. A slope-injection-restoration voltage profile for MIS-CELIV is also proposed to accurately determine the charge densities. The dynamic behavior of μe and μh is examined in five bulk heterojunction (BHJ) OSCs of polymer:fullerene (P3HT:PCBM and PffBT4T:PCBM) and polymer:nonfullerene acceptor (PM6:ITIC, PM6:IT4F, and PM6:Y6). While the former exhibits fast decays of μh and μe, the latter, in particular, PM6:IT4F and PM6:Y6, exhibits slow decays. Notably, the high-performing PM6:Y6 demonstrates both a balanced mobility (μe/μh) of 1.0-1.1 within 30 μs and relatively large CELIV-TRMC mobility values among the five BHJs. The results exhibit reasonable consistency with a high fill factor. The proposed new CELIV-TRMC technique offers a path toward a comprehensive understanding of dynamic mobility and its correlation with the OSC performance.

Optical conductivity and linear dichroism in monolayer C[formula omitted]N

We theoretically study the optical properties of monolayer C3N within the framework of linear response theory by using a two band effective k⋅p Hamiltonian. We find that both the effective masses and optical conductivities are anisotropic arising from the anisotropic band structure at the M point. Although the inter-band coupling only exists in the armchair (x-)direction, the effective mass along the armchair direction is larger than that along the zigzag (y-)direction. Interestingly, the absorption part of the optical conductivity Re σxx excited by linearly polarized light along the armchair direction is an order of magnitude larger than Re σyy excited by linearly polarized light along the zigzag direction, resulting in a strong linear dichroism, because the inter-band optical conductivity is dominated by inter-band coupling which only exists in the armchair direction. Finite doping can adjust the optical conductivities i.e., Re σxx and Re σyy and modulate the linear dichroism, but the effects of n-type doping and p -type doping are different because of the electron–hole asymmetry. Our results provide further understanding of the electronic state of monolayer C3N and maybe useful to design polarized optical devices based on it.

New pairing mechanism via chiral electron–hole condensation for non-BCS superconductivity

A novel chiral electron–hole (CEH) pairing mechanism is proposed to account for non-BCS superconductivity. In contrast to BCS Cooper pairs, CEH pairs exhibit a pronounced affinity to antiferromagnetism for superconductivity. The gap equations derived from this new microscopic mechanism are analyzed for both s- and d-wave superconductivity, revealing marked departures from the BCS theory. Unsurprisingly, CEH naturally describes superconductivity in strongly-correlated systems, necessitating an exceedingly large coupling parameter (λ>1 for s-wave and λ>π/2 for d-wave) to be efficacious. The new mechanism provides a better understanding of various non-BCS features, especially in cuprate and iron-based superconductors. In particular, CEH, through quantitative comparison with experimental data, shows promise in solving long-standing puzzles such as the unexpectedly large gap-to-critical-temperature ratio Δ0/Tc, the lack of gap closure at Tc, superconducting phase diagrams, and a non-zero heat-capacity-to-temperature ratio C/T at T=0 (i.e., the “anomalous linear term”), along with its quadratic behavior near T=0 for d-wave cuprates.

Investigations on the Carrier Mobility of Cs2NaFeCl6 Double Perovskites

Double perovskite materials have gradually become widely studied due to their potential applications in solar cells and other optoelectronic devices. We take Cs2NaFeCl6 as an example to investigate the carrier mobility with respect to the acoustic phonon and the optical phonon scattering mechanisms. By considering the deformation potential, carrier effective mass, and bulk modulus, the longitudinal acoustic (LA) phonon-determined mobilities for electrons and holes in Cs2NaFeCl6 are found to be μe = 2886.08 cm2 v−1 s−1 and μh = 39.09 cm2 v−1 s−1, respectively. The optical scattering mechanism involves calculating the Fröhlich coupling constant, dielectric constant, and polaron mass to determine the multiple polar optical (PO) phonon-scattering-determined mobilities, resulting in μe = 279.25 cm2 v−1 s−1 and μh = 21.29 cm2 v−1 s−1, respectively. By combining both interactions, the total electron mobility and hole mobility are determined to be 254.61 cm2 v−1 s−1 and 13.78 cm2 v−1 s−1, respectively. The findings suggest that the polarization of both electrons and ions, small coupling constant, and bulk modulus in Cs2NaFeCl6’s lattice make PO scattering a significant contribution to carrier mobility in this specific double perovskite, highlighting the importance of considering this in enhancing the optoelectronic properties of Cs2NaFeCl6 and other double perovskites.

Enhanced simulated sunlight photocatalytic performance in K2Ti6O13/g-C3N4 heterojunction

In this study, K2Ti6O[Formula: see text] (KTO) nanowires were doped with carbon (CKTO) via a novel solid-phase approach at 800∘C for the first time using ethanol, KF, and TiO2. In addition to the lower sintering temperature, a shorter insulation period was achieved compared to the conventional solid-phase method. Furthermore, by combining and calcining CKTO and g-C3N4, a CKTO/g-C3N4 heterojunction composite was produced. The rate at which CKTO/g-C3N4 photocatalytically degraded methylene blue was higher than those of pure CKTO and g-C3N4. Our study indicates that adding g-C3N4 enhances photocatalytic performance by reducing the recombination rate of photogenerated electron–hole pairs and narrowing the bandgap of the CKTO/g-C3N4 heterostructure. This paper presents a novel method for creating KTO composites in an eco-friendly and productive manner for the photocatalytic degradation of organic colors.

NaSCN‐Induced Cyano‐Rich Porous Graphitic Carbon Nitride with Sodium Dopant and Nitrogen Vacancies for Enhanced Photosynthesis of Hydrogen Peroxide

AbstractDefect engineering has been considered as an efficient and facile tactics to optimize the bandgap structure and improve the oxygen adsorption ability of graphitic carbon nitride (g‐C3N4). Herein porous g‐C3N4 with nitrogen vacancies and sodium dopant as well as cyano (─C≡N) groups has been successfully constructed by direct pyrolysis of melamine in the presence of cyano‐rich sodium thiocyanate (NaSCN). Moreover, the incorporation of NaSCN is interestingly found to induce the relative high content of ─C≡N groups compared to other inorganic sodium compounds (NaCl, NaOH, and Na2SO4), which has been experimentally demonstrated to be beneficial for extending the light absorption range and promoting the efficient separation of photo‐generated electron–hole pairs as well as improving the oxygen adsorption ability. Benefiting from the above features, the optimal photocatalyst exhibits high H2O2 yield of 438.2 µm within 4 h and excellent cyclic stability.

Integrated photodetectors embedded within fiber laser based on hybrid rGO:ZnO nanostructures

Online power monitoring is helpful in fiber-optic communication applications. This report introduced an innovative all-fiber photodetector based on the polished side of an arc-shaped fiber for the optical signals’ in situ measurements. For this purpose, a metal-semiconductor–metal photodetector was designed with multiple interdigitated metal fingers of gold electrodes. A waveguide structure containing polymethyl methacrylate (PMMA), graphene layers, and zinc oxide nanostructures was developed and covered over the arc-shaped fiber. Due to the PMMA’s refractive index (n = 1.4905), the evanescent field of propagating mode was drawn out of the core, thus increasing the light interaction with semiconductor nanostructures. To study the influence of graphene flakes on the optoelectrical behavior of zinc oxide nanostructures, a suspension of graphene oxide (GO) and ZnO nanorods was synthesized and transferred onto the PMMA thin film, which was deposited on the polished side of the arc-shaped fiber. The morphological analysis indicates the formation of ZnO nanorods with different orientations, and these nanorods have the potential to enhance incident photon trapping greatly. Upon photon exposure, the guiding photons in the fiber evanescently coupled with the deposited nanostructures, and the photoexcited electron–hole pairs were generated in the semiconductor material. Using applied voltage across the interdigitated electrodes, the generated excitons were separated and increased the photocurrent, which was monitored precisely by source-measure equipment. The optoelectrical properties of fabricated devices showed that incorporating graphene layers can improve the photon detection performance of the fabricated all-fiber photodetectors based on ZnO nanostructures.