Defect Trapping Research Articles

Highly efficient tunable white emission with ultralong afterglow in Sb3+/Mn2+-codoped CsCdCl3 crystals for multifunctional applications.

Recently, metal halides have attracted much attention due to their fascinating optical properties. However, achieving efficient white emission with ultralong afterglow remains a great challenge. Herein, we report Sb3+/Mn2+-codoped CsCdCl3 and multiple emission bands can be observed, which are derived from the self-trapped exciton emission of the Sb-Cl moiety and the d-d transition of Mn2+. Thus, tunable emission from cyan to orange light can be obtained. Moreover, efficient white emission with a luminous efficiency of 74% is observed when the energy-transfer efficiency from Sb3+ to Mn2+ is 34.5%. In particular, Sb3+/Mn2+-codoped CsCdCl3 shows bright orange afterglow emission, and the afterglow intensity is 1000 times that of CsCdCl3 and 20 times that of CsCdCl3:Mn2+. Upon combining this with thermoluminescence spectra, it is found that Mn2+/Sb3+ codoping can effectively regulate the depth and density distribution of trap defects, resulting in the ultralong afterglow duration exceeding 12 h at room temperature. Surprisingly, white light stimulation can provide additional photonic energy for Sb3+/Mn2+-codoped CsCdCl3, which enables the rapid release of trapped carriers to the emission center and rejuvenates afterglow emission after 12 h pre-delay. Finally, we demonstrated the applications of the as-synthesized compounds in single-component white light illumination, multiple optical anti-counterfeiting and information encryption.

Synergistic Optimization of Buried Interface via Hydrochloric Acid for Efficient and Stable Perovskite Solar Cells.

Incorporating chlorine into the SnO2 electron transport layer (ETL) has proven effective in enhancing the interfacial contact between SnO2 and perovskite in perovskite solar cells (PSCs). However, previous studies have primarily focused on the role of chlorine in passivating surface trap defects in SnO2, without considering its influence on the buried interface. Here, hydrochloric acid (HCl) is introduced as a chlorine source into commercial SnO2 to form Cl-capped SnO2 (Cl-SnO2) ETL, aiming to optimize the buried interface of the PSC. The incorporation of HCl into the SnO2 precursor solution works in two key ways. First, it converts the detrimental KOH stabilizer into KCl through an acid-base reaction. Second, it regulates the crystallization process of the perovskite, reducing PbI2 residues and voids at the buried interface. As a result, the efficiency of the PSC increases from 21.93% to 25.39%, with a certified efficiency of 25.69%, the highest efficiency reported for Cl-SnO2 ETL-based PSCs. Moreover, the target PSC exhibits excellent air stability, retaining 90% of its initial efficiency after 2900h of air exposure, compared to only 56.1% for the control PSC. This investigation highlights the effectiveness of HCl in the synergistic optimization of the buried interface in PSCs.

Does charge trapping affect subcritical crack growth behavior of yttria‐stabilized zirconia?

AbstractExposure to ionizing radiation has been known to affect the mechanical properties of solids; however, the exact mechanisms remain debated. In this study, we test the hypothesis that long lived metastable states formed by trapping of charges within defects influence subcritical cracking (SCC). Crack propagation rates were measured in 5 mol% Yttria‐stabilized zirconia samples, with and without prior exposure to Co‐60 gamma radiation (10 kGy absorbed dose). Crack growth was followed in situ by employing a double cantilever beam specimen inside an environmental scanning electron microscope (ESEM). In comparison with the unirradiated samples, an increased energy release rate of ∼10 J/m2 was required to maintain SCC in the irradiated samples conforming to an increase in SCC fracture resistance. Raman and x‐ray studies preclude any phase transformation and volume change due to irradiation; however, there was a significant change in optical absorption characteristics observed as the darkening of the irradiated sample. Thermally and optically stimulated luminescence measurements suggest that sample darkening is caused by metastable states that form due to charge trapping during radiation exposure. A closer examination of the SEM images demonstrates an increased number of microcracks ahead of the main crack in the irradiated specimens. We conclude that charge trapping in defects due to irradiation, and subsequent detrapping during crack propagation by mechanical stresses, initiate the formation of these microcracks. Consequently, energy is consumed during the interactions between the main crack and the developing microcracks, ultimately ensuing an overall increase in fracture resistance in the SCC regime.

Green preparation of nitrogen vacancies enriched g-C3N4 for efficient photocatalytic reduction of CO2 and Cr(VI)

Introducing vacancies has emerged as one of the valid strategies to modulate the photocatalytic performance of graphitic carbon nitride (g-C3N4). Introduction of nitrogen vacancies into g-C3N4 can create defect energy levels and trap electrons, consequently accelerating the separation of e−/h+ pairs and effectively boosting photocatalytic activity. Nitrogen vacancies can also serve as adsorption active sites, enhancing the adsorption capacity of the catalyst towards the target molecule (CO2). In this study, a series of g-C3N4 with abundant nitrogen vacancies were prepared using a green and facile strategy using sodium bisulfite treatment. Successful introduction of nitrogen vacancies endows with the photocatalyst more active sites, optimizes the band structure, significantly boosts the separation of photoexcited carriers, thereby remarkably enhancing photocatalytic CO2 and Cr(VI) reduction. On the 11CN photocatalyst (0.5 g g-C3N4 was treated by 11 g sodium bisulfite), the generation rate of CO and CH4 is 5.74 μmol·g−1·h−1 and 1.30 μmol·g−1·h−1, respectively, which is 3.19 times and 8.29 times higher than those on the reference g-C3N4 (CO: 1.37 μmol·g−1·h−1, CH4: 0.14 μmol·g−1·h−1). Under irradiation by three distinct monochromatic lights, the apparent quantum yield (AQY) of 11CN is also superior to that of the reference g-C3N4. Moreover, photocatalytic Cr(VI) reduction experiments were performed on the catalysts to demonstrate the universality of the catalysts The results show that the photocatalytic reduction rate constant of Cr(VI) by 11CN is 1.79 times higher than that over the reference g-C3N4. Stability of the catalyst was verified through cycling experiments, and the samples exhibit promising practical application prospect. The mechanism of photocatalytic CO2 reduction and the transformation pathway of intermediate products were elucidated using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). This study introduces a new strategy of introducing nitrogen vacancies into g-C3N4-based photocatalytic materials, providing an effective approach to enhance the photocatalytic activity of g-C3N4 in photocatalytic CO2 and Cr(VI) reduction.

Tunable nonlinear optical properties in polyaniline-multiwalled carbon nanotube (PANI-MWCNT) system probed under pulsed Nd:YAG laser

The investigation of the nonlinear optical (NLO) properties of polyaniline (PANI) and polyaniline doped with multi-walled carbon nanotube (PANI-MWCNT) in both solution and film forms was conducted using the open-aperture z-scan approach. A Q-switched resonant Nd: YAG laser with a wavelength of 532nm and two different fluences was utilized in this study. Based on the z-scan experiments, it was observed that the NLO behaviour of PANI and PANI-MWCNT composites exhibited a transition from reverse saturable absorption (RSA) to saturable absorption (SA) when the samples changed from a liquid to a film state. Two photon absorption (TPA) and thermally induced nonlinear scattering are the main mechanisms behind the RSA behaviour of the materials in solution form. The reason for SA behaviour of these materials in film form is attributed as the ground-state free electron bleaching in the conduction band due to the increased laser intensity. Due to increased structural disorder and the defect states or trap levels created by the dopants in the PANI system, the NLO properties of the PANI-MWCNT composite in both solution and film forms have significantly improved compared to those of pure PANI. Urbach tail analysis and carbon cluster determination revealed the presence of defect states in the composites system. The composite between PANI and MWCNT was verified using Fourier transform infrared (FTIR) spectroscopy. The functional elements present in the composites are verified by X-ray photoelectron spectroscopy. The NLO parameters of the samples, viz., the nonlinear absorption coefficient (β), the imaginary part of the nonlinear, and susceptibility χi(3) the figure of merit (FOM) of PANI-MWCNT, exhibited a notable enhancement in their values over PANI. Moreover, the PANI-MWCNT film demonstrated superior SA performance and the PANI-MWCNT solution demonstrated better OL performance compared to that of the PANI film and solution respectively. Also the effects of dopant induced structural modifications and lattice disorder on the NLO behaviour of these materials are correlated with the obtained NLO parameters. The tunable NLO properties accomplished by controlling the structural phase and dopant-induced defects enhance the possibility of these nanostructures for applications in optical limiting, optical switching, optical modulation, optical pulse compression and laser pulse narrowing.

Addressing the Defects within the Gate Oxide and at the Gate Oxide/Si Interface in Linear and Two-Dimensional Quantum Dot Arrays in Silicon

Some performance indicators of quantum computers can be traced back to the chip design and quality of materials comprising the quantum devices. Quantum states are fragile and may lose their state due to decoherence caused by a noisy environment [1,2,3]. Therefore, in addition to the growth of low-defect and low-disorder materials, reliable device fabrication with controlled densities of charge centers within the gate oxide and at the gate oxide/Si interface are also required.In this work, we report on state-of-the-art fabrication methods of linear and two-dimensional quantum dot array devices that are defined in isotopically purified in-house grown 28Si/SiGe heterostructures. Specifically, the two-dimensional quantum dot array devices presents a promising way forward for scaling up spin qubits, as such a device architecture allows for tunnel coupling between two adjacent quantum dots in two-dimensions [4]. However, scalable quantum processor might require the use of shared plunger and barrier gates, as demonstrated in the Ge/SiGe material platform [5], which entails a very high level of device uniformity in terms of potential landscape and associated control voltages required per qubit. Here, we report on electrical tuning of plunger gates performed in linear quantum dot array devices in order to achieve higher degree of electrical uniformity, thereby significantly reducing variations in the turn-on voltages [6]. Furthermore, following a similar electrical tuning procedure for plunger gates in a 2×2 two-dimensional quantum dot array devices enabled the realization of (1,1,1,1) charge state when all the plunger gates are set to 1 V, which may relax the requirements on control electronics and operations for spin qubit devices, as previously mentioned [7].In parallel to electrical tuning of the quantum dots, the electrical quality and defect densities of the gate dielectric and its interface with the semiconductor heterostructure are being studied for correlation with electrical tuning ability as well as device drift, jumps, and charge noise [8,9]. Specifically, we measure capacitance-voltage (CV), conductance-voltage (GV), and capacitance-time (C-t) data at room temperature on test structure devices in order to distinguish between mobile charge defects (Qm ), interface trap defects (Dit ), oxide fixed charge (Qf ) and dielectric non-linearities. As the next step, we are working to characterize the activities of these defects down to cryogenic temperatures and ultimately control their densities for optimal device performance.[1] Zwanenburg et al., Rev. Mod. Phys. 85, 961 (2013).[2] Nicollian and Brews, MOS (Metal Oxide Semiconductor) Physics and Technology, (John Wiley & Sons, New York, 1982).[3] Wuetz et al., arXiv: arXiv:2209.07242.[4] Vandersypen et al., npj Quantum Inf 3, 34 (2017).[5] Borsoi et al., Nature Nanotech 19, 21 (2024).[6] Meyer et al., Nano Letters 23, 2522 (2023).[7] Meyer et al., Nano Letters 23, 11593 (2024).[8] Wuetz et al., Nat Comms 14, 1385 (2023).[9] Esposti et al., npj Quantum Info 10, 32 (2024).

2D Memory Enabled by Electrical Stimulation‐Induced Defect Engineering for Complicated Neuromorphic Computing

AbstractDefect engineering is extensively utilized in 2D memory devices due to its effectiveness in enhancing charge‐trapping ability. However, conventional defect modulation techniques usually introduce only single types of carrier traps and cannot reconfigure trap types and densities after device fabrication. Here, for the first time, electrical stimulation‐driven long‐range migration of Cu ions within CuInP2S6 (CIPS) films is demonstrated to simultaneously introduce both electron and hole traps and enable reconfigurable modulation of interfacial defect trapping. This process is referred to as “electrical stimulation‐induced defect engineering”. By integrating these defect traps and the dual‐gate coupling effect, the memory window‐to‐scan range (MW/S.R) ratio, which reflects the device's charge trapping ability, doubled and peaked at 78.1% at Vbg = ± 80 V. Additionally, the dual‐gate memory device based on the graphene/CIPS/h‐BN/WSe2 heterostructure exhibits a maximum on/off ratio reaching 107 for multi‐level storage states, integrating neuromorphic computing and logic operations within a single platform. With 81 storage states and paired‐pulse facilitation (PPF), it achieves ≈90% accuracy in reservoir computing (RC) simulations. These results highlight the potential of electrical stimulation‐induced defect engineering for next‐generation electronics.

Construction of ultra-smooth and void-free buried interface via bilateral chemical bridging for efficient and hysteresis-suppressed perovskite solar cells

The surface properties are vital aspects in improving photovoltaic performance of perovskite solar cells (PSCs). Except for the upper surface of perovskite, the hidden buried interface which supports the beginning of perovskite film crystallization is of equal great importance for the construction of high-efficiency PSCs. Herein, we use urea phosphate (UPP) to build a bilateral chemical bridge in the buried interface under perovskite layer, to simultaneously improve the properties of SnO2 ETL and the upper perovskite. On one hand, the interaction between UPP and SnO2 passivates the defects of the SnO2 and facilitates the formation of ultra-smooth surface for superior interfacial contact. On the other hand, the chemical interaction between UPP and perovskite contributes to the optimization of crystal nucleation and growth, which improves the crystalline quality of perovskite, inhibits the formation of voids at the buried interface and reduces the defects of the grain boundary. Benefiting from the optimized buried interfacial contact, suppressed defects, accelerated charge extraction and modified energy level alignment, the UPP-processed device delivers an improved power conversion efficiency of 24.54 %, with effective suppression of hysteresis. Moreover, the stability of device is also improved owing to the reduction of trap defects. This work provides a feasible strategy to tune the buried interface between the charge transfer layer and perovskite layer for fabrication of efficient and stable PSCs.

Enhanced long-lasting luminescence nanorods for ultrasensitive detection of SARS-CoV-2 N protein

Persistent luminescence nanomaterials can remain luminescence when the light source is turned off, which exhibits promise in biosensor and bioimaging fields since they have the ability to completely eradicate tissue autofluorescence. Although significant progress has been made in the persistent luminescence biosensing, there is still a dearth of long-afterglow detection platform with low limit of detection (LOD) and high sensitivity. Herein, Zn2GeO4:Mn, Cr persistently luminescent nanorods (PLNRs) with superior persistent luminescence and long afterglow time were developed. The addition of Cr3+ manifestly improves persistent luminescence intensity and afterglow duration through creating a deep defect trap. Then the biosensors were constructed by combining the Zn2GeO4:Mn,Cr PLNRs-antibody and Fe3O4 magnetic nanoparticles (MNPs)-antibody for nucleocapsid protein detection based on electrostatic attraction. The LOD value for nucleocapsid protein realizes as low as 39.82 ag/mL, which is much lower than the previously reported persistent luminescent-based biosensors. Accordingly, the low detection sensitivity is attributed to fluorescence resonance energy transfer. In addition, high specificity is also achieved. Therefore, the as-prepared Zn2GeO4:Mn,Cr persistently luminescent materials can act as the promising candidate in biosensors applications. This strategy provides effective guidance for the development of biosensing platforms with high sensitivity and specificity.

Electronic Structure Engineering of Single-Atom Tungsten on Vacancy-enriched V3S4 Nanosheets for Efficient Hydrogen Evolution.

Constructing single-atom catalysts (SACs) and optimizing the electronic structure between metal atoms and support interactions is deemed one of the most effective strategies for boosting the catalytic kinetics of the hydrogen evolution reaction (HER). Herein, a sulfur vacancy defect trapping strategy is developed to anchor tungsten single atoms onto ultrathin V3S4 nanosheets with a high loading of 25.1wt.%. The obtained W-V3S4 catalyst exhibits a low overpotential of 54mV at 10mA cm-2 and excellent long-term stability in alkaline electrolytes. Density functional theory calculations reveal that the in situ anchoring of W single atoms triggers the delocalization and redistribution of electron density, which effectively accelerates water dissociation and facilitates hydrogen adsorption/desorption, thus enhancing HER activity. This work provides valuable insights into understanding highly active single-atom catalysts for large-scale hydrogen production.

Two-dimensional electronic conductivity in insulating ferroelectrics: Peculiar properties of domain walls

Ferroelectrics such as LiNbO3 (LN) are wide-band-gap insulators that may show a high local electric conductivity at the domain walls (DWs). The latter are interfaces separating regions of noncollinear polarization, which can be manipulated to build integrated nanoelectronic elements. In the present work, we model different DW types in LN from first principles. Our models reveal the DW morphology and shed light on their electronic properties: A strong band bending is predicted for charged DWs, leading to local metallicity. Defect trapping at the DW may further enhance the electric conductivity. Published by the American Physical Society 2024

Advanced spectroscopic methods for probing in-gap defect states in amorphous SiNx for charge trap memory applications

Silicon nitride (SiNx) serves as the charge trap layer in current 3D NAND flash memory devices. The precise formation mechanism and electronic structure of localized defect trap states in SiNx remain elusive. Here, we present a refined experimental methodology to elucidate the in-gap defect states and the band gaps in amorphous SiNx thin films. Our approach integrates high-resolution reflection electron energy loss spectroscopy (REELS) and spectroscopic ellipsometry (SE) for comprehensive analysis. By systematical analysis, we aim to provide a robust method for determining in-gap electronic states in SiNx. We investigated two different SiNx films prepared by plasma-enhanced chemical vapor deposition and sputtering. Our analysis revealed several distinct in-gap states and determined band gap energies. This approach not only provide advanced spectroscopic methods to characterize the defect electronic states in SiNx, but also applicable to other large band gap semiconductors or dielectrics to predict device-level characteristics for future devices.

Optically driven ultraviolet-C glowing from an in situ trapping-detrapping approach.

In recent years, the world has witnessed rapid progress in research on ultraviolet luminescent materials, ranging from high-level anticounterfeiting and solar-blind optical tagging to antibacterial applications. In particular, a background-signal free solar-blind surveillance of ultraviolet-C photons provides an opportunity in bright indoor and outdoor environments. However, ambient daylight or inevitable external photostimulation is always eliminated or underestimated in the research of persistent phosphors. Herein, an in situ trapping-detrapping experimental procedure is employed to reveal more information on the total trap energy and trap modulations after photostimulation. Our findings reveal the presence of optically active trapping defects with photostimulated detrapping and retrapping behavior. This work provides a fundamental advance in revealing the trap distribution and trap reshuffling during glowing-in-the-daylight events, offering what we believe to be new insights into manipulating traps.

Construction of homogeneous electron collection center at buried interface based on triazine-based graphdiyne for efficient perovskite solar cells

The properties of the buried interface between electron transport layer (ETL) and perovskite is critical factors to influence the performance of conventional perovskite solar cells (PSCs). Herein, functionalized triazine-based graphdiyne (Tz-GDY) nanospheres are prepared and employed to build up electron collection center and optimize the SnO2/perovskite interface. The pyrazine ring with homogeneous N element distribution and alkyne bond of Tz-GDY can passivate the undercoordinated Sn to remodel the electron density distribution around the Sn atoms and thus effectively eliminate the trap defects and inhibit the recombination loss significantly. In addition, the as-prepared Tz-GDY based nanospheres uniformly distribute at the SnO2/perovskite interface and a larger grain and more uniform perovskite film is obtained due to the increased contact angle. Moreover, Tz-GDY nanospheres can reduce the fermi energy level to facilitate the electron injection. Consequently, the Tz-GDY modified PSCs exhibits a champion power conversion efficiency of 24.83 % with effectively suppressed hysteresis. Our strategy proposes a more efficient electron collection method in buried interface, providing a guidance for constructing efficient PSCs.

Suppressing Ion Migration in MAPbI3 Polycrystalline Wafer with BMIMBF4 Ionic Liquid for X‐ray Detection and Imaging

Abstract3D lead‐halide perovskite wafers, recognized for their superior photoelectronic properties and robust fabrication, are promising candidates for advanced X‐ray detectors. However, severe ion migration in 3D perovskite wafers leads to dark current baseline drift and long‐term operational instability, hindering their further development. Herein, 3D MAPbI3 polycrystalline wafers with suppressed ion migration are prepared using the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4) and systematically investigated for X‐ray detection. The BMIMBF4‐passivated MAPbI3 wafers exhibit a low defect trap density (ntrap) of 9.45 × 109 cm−3, a high ion activation energy (Ea) of 0.51 eV, a notable iodide ion migration energy barrier of 0.65 eV, and a decreased dark current drift (Idrift) of 3.56 × 10−4 nA cm−1 s−1 V−1. The optimized MAPbI3 wafer‐based detectors exhibit a high sensitivity of 12088.8 µC Gyair−1 cm−2, a low detection limit (LoD) of 107.8 nGyair s−1, and strong operational stability in X‐ray detection. Moreover, these detectors demonstrate outstanding X‐ray imaging capabilities, achieving a high spatial resolution of 5.17 lp mm−1. Consequently, the utilization of ionic liquids with pseudo‐halide anions and polarized electron density distribution provides an innovative strategy for passivating 3D perovskite, advancing the field of powder‐pressed perovskite wafer X‐ray detection.

2D Gr/WSe2/MoTe2 vertical heterojunction for self-powered photodiode with ultrafast response and high sensitivity

Two-dimensional materials without lattice constraints can be combined into form heterojunctions via van der Waals forces, providing opportunities for the future development of novel high-performance photodetectors. In non-vertical heterojunction devices with long carrier transport channels, SRH recombination due to defect and interface states in the heterojunction and Langevin recombination due to Coulomb interactions induce large amounts of photogenerated carrier recombination, leading to low quantum efficiencies of the heterojunction. At the same time, defect and interface trap states, as well as the long channel of the non-vertical heterojunction device, lead to a slow response speed of the device. In this work, a 2D WSe2/MoTe2 vertical heterojunction photodiode with a transparent graphene top electrode has been designed to simultaneously achieve high sensitivity and fast response speed of photodetectors. Benefiting from the vertical device structure, high-quality interface and low contact resistance, the photogenerated electron-hole pairs can be efficiently separated and transported. The photodiode exhibits remarkable rectification characteristics with a rectification ratio as high as 1.4 × 104, and provides a broadband and self-powered photodetection from the visible to NIR bands (405–1064 nm) with a maximum responsivity of 0.33 A/W at 785 nm. In particular, the photodiode achieves an ultra-fast rise/fall time of 6.49/6.22 μs at 0 V and a further reduction of the response time to 1.68/1.2 μs at a reverse bias of −1 V. This ultra-fast response allows the photodiode to detect switching signals with a cutoff frequency of more than 70 kHz and 200 kHz at 0 V and −1 V, respectively. This work opens up new opportunities for the development of integrated 2D photodetectors with low power consumption, high sensitivity, and high speed.

InGaAs/GaAs nano-ridge laser with an amorphous silicon grating monolithically grown on a 300 mm Si wafer.

The monolithic growth of direct-bandgap III-V materials directly on a Si substrate is a promising approach for the fabrication of complex silicon photonic integrated circuits including light sources and amplifiers. It remains challenging to realize practical, reliable, and efficient light emitters due to misfit defect formation during the epitaxial growth. Exploiting nano-ridge engineering (NRE), III-V nano-ridges with high crystal quality were achieved based on aspect ratio defect trapping inside narrow trenches. In an earlier work, we used an etched grating to create distributed feedback lasers from these nano-ridges. Here we deposited an amorphous silicon grating on the top of the nano-ridge. Under pulsed optical pumping, a ∼7.84 kW/cm2 lasing threshold was observed, ∼5 times smaller compared to devices with an etched grating inside the nano-ridge. Compared to the etched grating, the amorphous silicon grating introduces no extra carrier loss channels through surface state defects, which is believed to be the origin of the lower threshold. This low threshold again demonstrates the high quality of the epitaxial deposited material and may provide a route toward further optimizing the electrically driven devices.

Passivated indium oxide thin-film transistors with high field-effect mobility (128.3 cm2 V−1 s−1) and low thermal budget (200 °C)

Here, we demonstrate a high-mobility indium oxide (In2O3) thin-film transistor (TFT) with a sputtered alumina (Al2O3) passivation layer (PVL) with a low thermal budget (200 °C). The sputtering process of the Al2O3 PVL plays a positive role in improving the field-effect mobility (µ FE) and current on/off ratio (I ON/I OFF) performance of the In2O3 TFTs. However, these enhancements are limited due to the high density of intrinsic trap defects in the In2O3 channels, as reflected in their large hysteresis and poor bias stability. Treating the In2O3 channel with oxygen (O2) plasma prior to sputtering the Al2O3 PVL results in notable improvements. Specifically, a high µ FE of 128.3 cm2V−1 s−1, a high I ON/I OFF over 106 at V DS of 0.1 V, a small hysteresis of 0.03 V, and a negligible threshold voltage shift under negative bias stress are achieved in the passivated In2O3 TFT (with O2 plasma pretreatment), representing a significant improvement compared to the passivated In2O3 TFT (without O2 plasma pretreatment) and the unpassivated In2O3 TFT. The remarkable reduction of intrinsic trap defects in the passivated In2O3 TFT compensated by O2 plasma is the primary mechanism underlying the improvement in µ FE and bias stability, as validated by x-ray photoelectron spectra, hysteresis analysis, and temperature-stress electrical characterizations. Plasma treatment effectively compensates for intrinsic trap defects in oxide semiconductor (OS) channels, when combined with sputter passivation, resulting in a significant enhancement of the overall performance of OS TFTs under low thermal budgets. This approach offers valuable insights into advancing OS TFTs with satisfactory driving capability and wide applicability.

Advancements in bandgap engineering: bromide-doped cesium lead perovskite thin films

Perovskite materials have emerged as promising candidates for next-generation photovoltaic devices due to their unique optoelectronic properties. In this study, we investigate the incorporation of bromine into cesium lead mixed iodide and bromide perovskites (CsPbI3(1-x)Br3x) to enhance their performance. By depositing films with varying bromine concentrations (x = 0, 0.25, 0.5, 0.75), we employ a combination of structural and optical characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy, and photoluminescence. Our analysis reveals that introducing bromine leads to structural modifications, influencing the perovskite films’ optical properties and energy gap. Specifically, we observe semiconductor behavior with a tunable energy gap controlled by the intercalation of bromine atoms into the CsPbI3 lattice. Furthermore, heat treatment induces phase transitions in the perovskite films, affecting their optical responses and crystalline quality. SCAPS-1D simulations confirm the improved stability and efficiency of bromine-doped CsPbI3 films compared to undoped counterparts. Our findings demonstrate that bromine incorporation facilitates the formation of highly crystalline perovskite films with reduced trap defects and enhanced carrier transport properties. These results underscore the potential of bromine-doped CsPbI3 perovskites as promising materials for high-performance photovoltaic applications, paving the way for further optimization and device integration.

Natural Chelating Agent-Treated Electron Transfer Layer for Friendly Environmental and Efficient Perovskite Solar Cells.

In perovskite solar cells (PSCs), the electron transfer layer (ETL) characteristics have significant effects on the photoelectric conversion efficiency (PCE) of the devices. Herein, a natural chelating agent polymer polyaspartic acid (PASP) is doped into the SnO2 precursor solution attributed to a strong interaction between PASP molecules and SnO2, which strengthens the interface contact and passivates the vacancy oxygen trap of the obtained SnO2 ETL, thus promoting the transfer of electrons. In addition, PASP can also regulate the growth of perovskite crystals, leading to an improved crystal quality of the perovskite films. Meanwhile, there is an excellent chelate anchoring of PASP to uncoordinated Pb2+, facilitating the reduction of trap defects at the interface, improving the stability of device, and suppressing the leakage of toxic Pb. Finally, the photovoltaic performance of the optimized device was greatly improved, and the PCE was increased from 21.22 to 23.49%, with outstanding environmental stability. This work provides an inexpensive and efficient treatment strategy that improves the performance and stability of friendly environmental PSCs.