Carrier Generation Rate Research Articles

Optimization of Sr3NCl3-based perovskite solar cell performance through the comparison of different electron and hole transport layers

Strontium Nitride Trichloride (Sr3NCl3) is a promising absorber material for solar cells due to its unique structural, electrical, and optical properties. We conducted a thorough investigation to scrutinize the structural, optical, and electronic characteristics and the photovoltaic efficiency of double-heterojunction solar cells utilizing Sr3NCl3 absorbers. Various metals were evaluated for the front and rear contacts to determine the optimal metal-semiconductor interface, with the study determining that silver (Ag) is the most suitable option for the front contact and nickel (Ni) for the back contact. The PV performance of innovative Sr3NCl3 absorber-based cell structures was evaluated with two different Hole Transport Layers (HTLs), MASnBe3 and CBTS, alongside ZnO and WS2 serving as the transition metal dichalcogenide (TMD) Electron Transport Layers (ETLs). This investigation examined a range of factors, such as layer thickness, operational temperature, doping density, defect densities at both the interfaces and within the bulk, carrier generation and recombination rates, quantum efficiency (QE), series versus shunt resistance, absorption coefficient, and current density-voltage (J-V) characteristics, utilizing the SCAPS-1D simulator software. Fine-tuning of both two HTL and ETL revealed that the highest power conversion efficiency (PCE) of 27.34 % with JSC of 19.78 mA/cm2, fill factor (FF) of 88.84 %, and VOC of 1.56 V was achieved with MASnBe3 HTL and ZnO ETL, while the lowest PCE of 25.55 %, with JSC of 19.77 mA/cm2, FF of 89.07 %, and VOC of 1.45 V was obtained for CBTS HTL and WS2 ETL, respectively. These findings highlight the promising potential of Sr3NCl3 absorbers with ZnO as ETL and MASnBe3 as HTL for developing advanced perovskites heterostructure solar cells for enhanced performance in the future.

Hot carriers from intra- and interband transitions in gold-silver alloy nanoparticles

Hot electrons and holes generated from the decay of localised surface plasmons in metallic nanoparticles can be harnessed for applications in solar energy conversion and sensing. In this paper, we study the generation of hot carriers in large spherical gold-silver alloy nanoparticles using a recently developed atomistic modelling approach that combines a solution of Maxwell’s equations with large-scale tight-binding simulations. We find that hot-carrier properties depend sensitively on the alloy composition. Specifically, nanoparticles with a large gold fraction produce hot carriers under visible light illumination while nanoparticles with a large silver fraction require higher photon energies to produce hot carriers. Moreover, most hot carriers in nanoparticles with a large gold fraction originate from interband transitions which give rise to energetic holes and ‘cold’ electrons near the Fermi level. Increasing the silver fraction enhances the generation rate of hot carriers from intraband transitions which produce energetic electrons and ‘cold’ holes. These findings demonstrate that alloy composition is a powerful tuning parameter for the design of nanoparticles for applications in solar energy conversion and sensing that require precise control of hot-carrier properties.

Influence of Illumination Spectrum on Dissociation Kinetics of Iron–Boron Pairs in Silicon

Photodissociation kinetics of iron–boron (FeB) pairs in boron‐doped Czochralski silicon is studied experimentally using different light sources. It is shown that the FeB dissociation rate depends not only on integrated light intensity and overall carrier generation rate, but also on spectral composition of illumination. The value of the material constant of dissociation K varies and has been determined to be within s. The investigation reveals an increase in the dissociation rate with increase in photon energy. The results indicate that recombination‐enhanced defect reaction is the primary factor in the second stage of pair dissociation.

Carrier transport simulation methods for electronic devices with coexistence of quantum transport and diffusive transport

In this manuscript, carrier transport simulation methods are proposed for devices with the coexistence of quantum transport and diffusive transport by combining the nonequilibrium Green's function method with the drift-diffusion transport simulation method. Current continuity between quantum transport and drift-diffusion transport is ensured by setting quantum transport current as the connection boundary condition of drift-diffusion simulation or by introducing quantum transport-induced carrier generation rates to drift-diffusion simulation. A comprehensive study of our method and the method combining the Wentzel–Kramers–Brillouin (WKB) method with the drift-diffusion transport simulation method is performed for n-type tunnel oxide passivating contact solar cell to investigate their applicable conditions and balance the accuracy and computational cost. As the oxide barrier width, barrier height, and electron effective mass increase, or the doping concentration in the electron transport layer decreases to the extent that the blocking effect of the oxide barrier on light-generated electrons becomes significant, method I is more accurate since the transmission coefficient near the conduction band edge calculated by WKB is overestimated; otherwise, method II is more suitable due to its low computational cost without the loss of accuracy. In addition, the differences between current densities, carrier densities, and Shockley–Read–Hall recombination rates simulated under the two current continuity conditions for the solar cell with different carrier mobilities are also further explored and analyzed.

Performance investigation of ferroelectric L-shaped tunnel FET with suppressed corner tunneling for low power applications

In this work, a ferroelectric L-shaped tunnel FET (FE-LSTFET) is introduced to offer improvement in various DC and analog/high-frequency parameters. In this design, the incorporated FE layer enhances the vertical electric field at the source-channel interface, which improves the tunneling rate of charge carriers during the ON-state. The effect of negative capacitance (NC) and L-shaped N+ pocket causes dominance of vertical tunneling over corner tunneling (mainly at low gate voltages), which in turn reduces the transition voltage and current from 0.85 to 0.25 V and 1.2 × 10-8 to 5.67 × 10-11 A/µm respectively, thereby improving parameters such as ION, IOFF, and SSavg. Further, optimization of the thickness and doping concentration helps to keep the N+ pocket in fully depleted mode and consequently, ION/IOFF is increased from 0.3 × 1012 to 1.2 × 1014 and SSavg is reduced from 52 to 30 mV/decade. Subsequently, NC parameters such as remanent polarization (Pr) and coercive electric field (Ec) are optimized to increase the memory window, which further improves the read margin of FE-LSTFET as a memory device. Furthermore, TCAD-based simulation results show that optimizing the FE thickness improves ION and IOFF in the order of ∼ 1 and ∼ 2, respectively compared to those of C-LSTFET. With an optimum drain-overlap length, IOFF is shown to reduce from 6.6 × 10-17 to 5.43 × 10-19 A/µm due to a reduction in the SRH generation rate of the charge carriers. Despite the degradation in Cgg due to drain-overlap by the stack of FE and SiO2 layers, a significant increase in e-BTBT helps in achieving a transconductance of 2.48 × 10-4 S/µm, thus leading to a large cut-off frequency of 34.12 GHz. Next, analysis of the FE-LSTFET-based inverter shows significant improvements in several parameters including propagation delay and full swing. Moreover, FE-LSTFET shows more reluctance to self-heating effects than C-LSTFET as ION/IOFF is increased by an order of ∼ 3 at 500 K. Lastly, the performance of FE-LSTFET is benchmarked with existing TFET designs indicating that FE-LSTFET is suitable as a high-speed and low-power memory device.

Investigation of FABr treatment's potential for triple-cation multi-halide perovskite solar cells

In order to preserve the effectual potential of triple-cation coupled with multi-halide perovskites (PVTs), the phase-related conflict amongst different precursors has to be resolved. There arises the necessity of post-growth passivation treatments, especially using formamidinium bromide (FABr) upon such PVT films. In this research, a methodical comparison assessment is performed on triple-cation, multi-halide (CsFAMAPbIBr)-based PVT solar cells (PSCs) with and without FABr passivation using numerical study. A meticulous estimation of all the performance parameters of both PSCs was implemented in accordance with transformations in thickness, effective density, and acceptor density of the PVT absorber layer together with the charge transport layer thickness variations. The investigation revealed that the charge carrier generation rate remained the same after FABr passivation, however,the recombination rate was lowered by ∼ 32 % (from 7.27 × 1021 to 4.92 × 1021 cm-3s−1). The analysis discerned that at minimum valence band effective density of PVT absorber: 1 × 1017 cm−3, FABr-treated CsFAMAPbIBr-based PSC ensures the highest power conversion efficiency of 24.62 % against its un-passivated correspondent of 22.25 %. Further, this investigation imparts the remarkableness of FABr passivation treatment in regulating the overall performance of triple-cation and multi-halide-based PSCs.

Enhanced DSSC efficiency through integration of red-emitting MgAl2O4: Eu3+ phosphor within TiO2 layer

The main objective of this paper was to enhance the absorption and charge carrier generation rates of DSSC. The functional property of the Eu3+ ion (red light) when infused with the MgAl2O4 host was combined with TiO2 nanoparticles and the results obtained through various studies are elaborated. The host and the nanoparticles were prepared through solid-state and sol-gel routes, respectively, with their crystalline structure and surface morphology identified by X-ray diffraction and field emission scanning electron microscope. The optical characteristics of the sample were studied through photoluminescence (PL) excitation (394 nm) and PL emission spectral analysis. The MgAl2O4: Eu3+ phosphor utilized in DSSC for the light down-conversion process converts high-energy incident light into low-radiation light, which further excites the N719 dye to emit charge carriers, thus increasing the conversion efficiency of the dye-sensitized solar cells. The overall conversion efficiency was observed a 4.80 % when 0.9 MW % Eu3+: MgAl2O4 was added to the TiO2 nanoparticle with an enhanced DSSC performance.

Simulation and numerical modeling of CuO films thickness influence on the efficiency of graphite/CuO/Ni solar cells

AbstractCopper oxide is one of the original semiconductor materials employed for solar cells in the early 19th century before Silicon solar cells became popular due to their abundant availability, and eco‐friendly nature. The optoelectronic parameters signify its huge potential in solar cell devices, though it's far from the theoretically predicted performance, provides tremendous scope to improve the solar cell performance by forming different heterojunctions. In this study, we investigated the copper oxide's (CuO) potential as an active layer in thin‐film solar cells theoretically with a new structure consisting of a Glass/ITO/Graphite/CuO/Ni. Furthermore, the charge carrier's generation rate and theoretical thresholds for photovoltaic device efficiency were determined for varying active layer thicknesses by employing a normalized light intensity equivalent to that of the AM1.5 spectrum. The optimized performance of the simulated structure by considering realistic optical parameters of the solar cell was ~24%, obtained for the 500 nm CuO films. The performed theoretical work can help to employ CuO and boost the performance of solar cells experimentally.

Critical role of dopant in NiOx hole transport layer for mitigating redox reactivity at NiOx/absorber interface in mixed cation perovskite solar cells.

Redox chemistry transpiring at the interface of NiOx hole transport layer (HTL) and perovskite absorber is a critical phenomenon leading to relatively low values of open circuit voltage (VOC) and fill factor (FF), in turn hampering the overall device performance and stability. In this work, for the first time, the hard acid electronic nature of vanadium (V) dopant in nickel oxide HTL is opportunely exploited to mitigate the undesirable Lewis acid-base reactions occurring at the HTL/mixed-cation perovskite interface. The findings of the study show that vanadium doping results in improved interfacial energetics along with decreased VOC loss, confirming that despite the increase in Ni3+/Ni2+ ratio with the vanadium dopant, the redox reaction catalyzed by Ni3+ ions is kept under check. Vanadium doping also aided in the realization of superior perovskite films with lower Urbach energy, which translated into one order increase in maximum photoinduced carrier generation rate per unit volume. Carrier dynamics investigations show fewer defect states (lower VTFL) and trap-assisted recombination (lower diode ideality factor), which optimize the devices' photovoltaic performance. These benefits collectively contribute to low-loss charge transfer across the NiOx/mixed-cation perovskite interface, which increases the relative efficiency by ∼30% for 5 wt% V-doped NiOx devices compared to pristine NiOx devices, augmented by an increase in device J-V parameters like open circuit voltage (VOC), short circuit current density (JSC), and fill factor (FF).

Artificial neural network models for metal-ferroelectric-insulator-semiconductor ferroelectric tunnel junction memristor

Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structure ferroelectric tunnel junction (FTJ) memristor becomes one of the most promising candidates for next-generation memories. Two numerical simulation methods have been developed and analyzed previously to calculate the tunneling current in the MFIS-FTJ, one by using the Wentzel–Kramers–Brillouin (WKB) method with the band profile obtained from Poisson's equation, the other by self-consistently solving Poisson's equation and the drift-diffusion transport equations with a tunneling-induced carrier generation rate. However, numerical methods can be computationally expensive, especially for device design with various parameters. In this work, an artificial neural network (ANN) model that can predict the device performance is proposed, the model can reduce computational cost while maintaining good accuracy. In addition, to further investigate the applicable conditions of the two simulation methods mentioned above, we also develop an ANN model to predict the relative differences between the two methods' results under different conditions, and the prediction results show good agreement with numerical results.

Improved optical performance of CH3NH3PbI3 perovskite-germanium heterostructure photodetectors assisted by a periodic nanosphere array

The methylammonium lead iodide (CH3NH3PbI3)-germanium (Ge) heterojunction with a layer of periodic nanospheres was numerically studied to achieve improved performance over broadband from 300 nm to 1600 nm by the 3D finite element method (FEM). Under AM 1.5 g illumination, the total absorbed power increased 14% in heterojunction photodetectors assisted by an Al2O3 antireflection (AR) array, after optimizing the thickness of perovskite and Ge, as well as the radius, period and material type (metal or dielectric permittivity) of nanosphere array by genetic algorithm, with reference to a corresponding device without nanospheres. The enhanced optical properties were further elaborated and demonstrated by comparatively analyzing broadband absorptance, electric field distributions, absorbed power distributions and the optical generation rate of charge carriers in the two photodetector models. The proposed perovskite-Ge heterojunction with spheres shows great promise for optoelectronic devices.

Interfacial lattice coupling engineering in all-inorganic coupled flexible films for dielectric energy storage

Hexagonal boron nitride (BN) was dispersed into the lattice of Sr2Bi4Ti5O18 (SBT) ferroelectrics to form all-inorganic flexible film capacitors. The interfacial lattice coupling in microscopic induces reconstruction of lattice and electron configuration. The electrons transfer interaction at the interfacial lattices results in the lattice stretching, thereby enhancing polyhedral dipole-dipole interactions. Meanwhile, the potential difference derived from the electron transfer provides driving force for the interfacial polarization. Above both effectively enhance the polarization without expense of breakdown strength. The interfacial lattice coupling greatly reduces the carrier generation rates under high electric field due to the ultra-high bandgap of BN, which further improves breakdown strength, thus, suppressing the inversed relationship. The recovery energy density of 119.7 J/cm3 and the efficiency of 71.2 % are obtained with a consecutive mechanical bending stability. This strategy provides an alternative to break through the inversed relationship between polarization and breakdown strength for all-inorganic flexible film capacitors.

Directional surface hydroxylation on 6H-SiC induces surface electron polarization and proton activation promoting photocatalytic water splitting for hydrogen

Photocatalytic water splitting for hydrogen production is a promising solution to converse solar energy to green fuel. A high-performance photocatalyst system always requires fast surface reaction rate and efficient charge separation. Herein, a novel strategy that photo-assisted silanizing-hydrolyzing method is used to trigger in situ surface hydroxylation selectively on Si atoms of micro-sized 6H-SiC particles. Due to this functionalization, the results show that the silanizing-hydrolyzing process occurs at the Si sites while the C is passivated, leading the Si atoms with electron deficiency property by XPS characterization. It also drives the SiC surface from native hydrophobicity to hydrophilicity, which is benefit to proton absorption and desorption of generated H2 by FT-IR and contact angle (CA) result. Furthermore, the photo-electron-chemical characterization demonstrate the charge migration and separation of SiC are promoted. The DFT calculation further indicates these surface properties changes are mainly attribute to the surface electron polarization through the hydroxylation, inducing the Si-O spatial charge separation. More importantly, the positive Si atoms exhibit an appropriate proton absorption energy, resulting in easily H2 desorption from SiC surface. The hydrogen evolution is significantly enhanced by 33 times compared to pristine SiC without any cocatalysts introduced. Our method provides an efficient route to design an environmental-friendly photocatalytic material SiC and construct highly efficient solar energy conversion systems, which can simultaneously facilitate carrier generation, transportation and surface reduction reaction rate.

Enhanced visible light photocatalytic activity of nanostructured SiO2-TiO2 thin films through optimizing thickness

Thin films of silicon dioxide-titanium dioxide (SiO2-TiO2) with different thicknesses were deposited by a simple dip-coating method in a repetition behavior followed by heating processes. Choosing the optimum thickness is accounted as an approach for improving photocatalytic and hydrophilicity properties of a thin film. The obtained results from FESEM and AFM characterizations showed that with increasing thickness, the surface roughness increases from 3.089 nm to 132.8 nm. The XRD patterns indicate the presence of anatase phase for the SiO2-TiO2 thin film. Optical measurements were used to calculate thickness, generation rate of photocarriers, band gap, and refractive index of the samples. Decrease of band gap with increasing thickness makes the layer more proper for photocatalytic activity under visible light. It is obtained that the generation rate of carriers has the highest value (17.16 × 1024 m−3s−1) for the thickness of 336 nm. PL spectra for the thickness of 336 nm confirmed the presence of defects which reduce the recombination rate and improve charge carrier separation. XPS was used to distinguish the chemical composition. Variation of defect concentrations, number of grain boundaries, and surface roughness with thickness were considered as the main parameters affecting the photocatalytic performance. The highest photodegradation was obtained for 336 nm thick film under illumination of visible light (100% degradation of 40 ml solution of 10 mg l−1 methylene blue (MB)). This research provides a systematic study on the structural and optical properties of the different thick SiO2-TiO2 films with goal of enhancing photocatalytic activity in the visible light region.

Synergistic photocatalytic performance through Z-Scheme charge transfer in organic dye degradation using α-MnO2 nanorods and Co3O4 nanoparticles combined with eggshell derived hydroxyapatite

HAp-α-MnO2-Co3O4 nanocomposite was prepared by the wet impregnation technique. Various analytical techniques were used to study the structural, morphology and photophysical characteristics. In the present study, the degradation of MB dye under the visible light irradiation in existence of HAp-α-MnO2-Co3O4 nanocomposite has been examined and the detailed mechanism for the photocatalytic degradation was discussed. The improved photocatalytic degradation activity over the HAp-α-MnO2-Co3O4 nanocomposite can be ascribed to the efficient high generation and low recombination rate of charge carriers under the UV-Visible light. Also, the key features for HAp-α-MnO2-Co3O4 nanocomposite including enhancement of light absorbance, recombination rate of photogenerated charge carriers have also been found for the nanocomposites. Based on photocatalytic degradation, it was found that the HAp-α-MnO2-Co3O4 nanocomposite has the highest photocatalytic activity among all freshly prepared samples. In particular, the MB dye was almost completely degraded (95.5 %) by exposure to UV–visible light in 60 min of irradiation, the observed degradation result was relatively higher than that of pristine HAp, α-MnO2 and Co3O4, respectively. HAp-α-MnO2-Co3O4 nanocomposite efficiently degraded 94.42 % colorless phenol, demonstrating its dual ability to break down hazardous dyes and organic compounds under the same conditions. In addition, the HAp-α-MnO2-Co3O4 nanocomposite has a good recyclability of 90.25 % after five successive cycles. These observed results show that the HAp-α-MnO2-Co3O4 nanocomposite is an environmentally friendly material for environmental remediation.

Simulations and Suitability Study of Inorganic Cu‐Based Hole‐Transport Layers in Planar CH3NH3SnI3‐Based Perovskite Solar Cell and Module

Hybrid perovskite light‐harvesting materials offer a high absorption coefficient, solution‐based synthesis techniques, and tunable bandgap, making them ideal for high‐performance renewable energy devices. The primary focus of current investigations is the design and comparative numerical investigation of solar cells. Key aspects with a substantial influence on device output, such as quantum efficiency, surface depth, bandgap tuning, interfacial defect densities, thicknesses of structural layers, temperature, carrier generation, and recombination rates, are explored and optimized. The investigation of Cu‐based hole‐transport layers (HTLs) has revealed that Cu2O (power conversion efficiency [PCE] = 22.60%), CuCrO2 (PCE = 22.25%), and CuI (PCE = 21.54%) have shown remarkable photovoltaic parameters with high carrier generation and reduced recombination rates. CuCrO2 has shown significant electrical parameters, which are further incorporated into the module simulation software PVsyst. Calculations are performed with a combination of 72 cells in series for a solar module of standard weight 27 kg and dimensions 2.20 m × 1.10 m in Islamabad, Pakistan. The module has shown an impressive power output of 523.40 W and an annual performance ratio of 88.6%. Simulated results endorse a viable and technically feasible route to incorporate Cu‐based HTLs into the design of perovskite absorber‐based solar cells and modules to increase their efficiency and maximize power production.

A comprehensive photovoltaic study on tungsten disulfide (WS2) buffer layer based CdTe solar cell

Transition metal di-chalcogenides (TMCDs)-Tungsten disulfide (WS2) exhibit excellent optoelectronic properties such as suitable bandgap, high absorption coefficient, good conductivity, high carrier mobility, etc. to be used as a photovoltaic material for thin-film solar cells. In the present work, we have replaced the traditional buffer CdS and ITO/ZnO window layer in CdTe solar cells with the non-toxic, earth-abundant WS2 buffer and SnO2 window layer, respectively. The SCAPS-1D solar simulator is used to investigate the potentiality of WS2 as buffer material in CdTe solar cells. This numerical study provides a comparison of the performances between the proposed structure: SnO2/WS2/CdTe/Au and the baseline structure: ITO/ZnO/CdS/CdTe/Au. The impacts of the charge carrier generation rate, spectral response, current-voltage characteristics, bulk defect density, defect density at buffer/absorber interface, operating temperature, and capacitance-voltage characteristics on the solar cell performance parameters have also been analyzed. The tolerance level of defect density in WS2 bulk and WS2/CdTe interface are found to be 1017 cm−3 and 1012 cm−3, respectively. The temperature study reveals the poor structural robustness and thermal stability of the proposed cell. The conversion efficiency of the proposed cell has found to be 20.55% at the optimized device structure. Nevertheles, these findings may provide an insight to fabricate viable, environment friendly, and inexpensive CdTe thin-film solar cells.

Investigation of high-temperature performance of WO<sub>3</sub>/<b><i>β</i></b>-Ga<sub>2</sub>O<sub>3</sub> heterojunction deep-ultraviolet photodetectors

Owing to the high bandgap of up to 4.8 eV, Ga<sub>2</sub>O<sub>3</sub> has a natural advantage in the field of deep-ultraviolet (DUV) detection. The Ga<sub>2</sub>O<sub>3</sub>-based photoconductors, Schottky and heterojunction detectors are proposed and show excellent photodetection performance. The Ga<sub>2</sub>O<sub>3</sub> heterojunction detectors are self-driven and feature low power consumption. On the other hand, considering the ultra-wide bandgap and low intrinsic carrier concentration, Ga<sub>2</sub>O<sub>3</sub>-based photodetectors are exhibiting important applications in high-temperature photodetection. In this work, a WO<sub>3</sub>/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub> heterojunction DUV photodetector is constructed and the effect of high temperature on its detection performance is investigated. The <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> films are prepared by metal-organic chemical vapor deposition (MOCVD), and WO<sub>3</sub> films and Ti/Au ohmic electrodes are prepared by spin-coating technology and magnetron sputtering technique, respectively. The current-voltage (<i>I-V</i>) and current-time (<i>I-t</i>) measurements are performed at different ambient temperatures. Parameters including light-dark-current ratio (PDCR), responsivity (<i>R</i>), detectivity (<i>D</i><sup>*</sup>), and external quantum efficiency (EQE) are extracted to evaluate the deep-ultraviolet detection performance and its high-temperature stability. At room temperature (300 K), the PDCR, the <i>R</i>, the <i>D</i><sup>*</sup>, and the EQE of the detector are 3.05×10<sup>6</sup>, 2.7 mA/W, 1.51×10<sup>13</sup> Jones, and 1.32%, respectively. As the temperature increases, the dark current of the device increases and the photocurrent decreases, resulting in the degradation of the photodetection performance. To explore the physical mechanism behind the degradation of the detection performance, the effect of temperature on the carrier generation-combination process is investigated. It is found that the Shockley-Read-Hall (SRH) generation-combination mechanism is enhanced with the increase of temperature. Recombination centers are introduced from the crystal defects and interfacial defects, which originate mainly from the SRH process. Specifically, the dark current comes mainly from the depletion region of WO<sub>3</sub>/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub>, and the carrier generation rate in the depletion region is enhanced with temperature increasing, which leads to the rise of dark current. Similarly, the increase of temperature leads to the improvement of the recombination process, therefore the photocurrent decreases at a higher temperature. This effect can also well explain the variation of response time at a high temperature. Overall, it is exhibited that the WO<sub>3</sub>/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub> heterojunction photodetector can achieve stable self-powered operation even at an ambient temperature of 450 K, indicating that the all-oxide heterojunction detector has potential applications in harsh detection environments.

Thermal Activation of PEDOT:PSS/PM6:Y7 Based Films Leads to Unprecedent High Short‐Circuit Current Density in Nonfullerene Organic Photovoltaics

AbstractFinding an effective approach to suppress trap formation is a potential route for enhancing the performance of nonfullerene organic photovoltaic (NF‐OPVs) devices. Here, an extraordinary short‐circuit current density (JSC) value of 32.65 mA cm‐2 is achieved, higher than the state‐of‐the art NF‐OPVs reported, reaching a high power conversion efficiency (PCE) of 17.92%. This remarkable enhancement is exhibited through the fine‐tuning of PEDOT:PSS/PM6:Y7 films and interface morphologies via applying the prethermal treatment approach (Pre‐TT) to the devices, which exhibit JSC and PCE enhancement of 21% and 8%, respectively, compared to the pristine devices. Accordingly, the dependence of the JSC upon the Pre‐TT approach through a range of morphological, optical, electrical, and advanced transient measurements is investigated. The Pre‐TT‐based films are found to possess optimal smooth blend morphology with better dispersity owing to reduced domain size. Moreover, the measurements show that the optimized treated devices present higher exciton dissociation probabilities and generation rate of the free charge carriers, showing an ideal balanced electron/hole mobility that reveals the JSC and PCE enhancement. Hence, Pre‐TT approach provides a facile passivation strategy that reduces the trap state density of the blend film, improves interface charge transfer, allows balanced electron/hole mobility, and thus promotes device performance.

Study of Vertical Ga2O3 FinFET Short Circuit Ruggedness using Robust TCAD Simulation

In this paper, the short circuit ruggedness of Gallium Oxide (Ga2O3) vertical FinFET is studied using Technology Computer-Aided-Design (TCAD) simulations. Ga2O3 is an emerging ultra-wide bandgap material and Ga2O3 vertical FinFET can achieve the normally-off operation for high voltage applications. Ga2O3 has a relatively low thermal conductivity and, thus, it is critical to explore the design space of Ga2O3 vertical FinFETs to achieve an acceptable short-circuit capability for power applications. In this study, appropriate TCAD models and parameters calibrated to experimental data are used. For the first time, the breakdown voltage simulation accuracy of Ga2O3 vertical FinFETs is studied systematically. It is found that a background carrier generation rate between 105 cm−3s−1 and 1012 cm−3s−1 is required in simulation to obtain correct results. The calibrated and robust setup is then used to study the short circuit withstand time (SCWT) of an 800 V-rated Ga2O3 vertical FinFET with different inter-fin architectures. It is found that, due to the high thermal resistance in Ga2O3, to achieve an SCWT >1 μs, low gate overdrive is needed which increases Ron,sp by 66% and that Ga2O3 might melt before the occurrence of thermal runaway. These results provide important guidance for developing rugged Ga2O3 power transistors.