Physics

Tb-doped semiconductors are candidates for novel full-color light sources in next-generation high-definition displays. Particularly, Tb-doped AlxGa1−xN (AlxGa1−xN:Tb) has attracted much attention because Tb3+ ions doped into AlxGa1−xN show ultra-stable multi-color emissions consisting of blue, green, yellow, and red. Herein, we demonstrate room-temperature operation of AlxGa1−xN:Tb light-emitting diodes (LEDs) under current injections and characterize the optical/electrical properties. Ultra-stable Tb3+ emissions with narrow linewidths are clearly observed, and it is revealed that the quantum efficiencies monotonically increase for Al-richer conditions. Furthermore, the LEDs fabricated on AlN templates show superior optical and electrical properties to those on GaN templates because Al-rich AlxGa1−xN:Tb layers are coherently grown on the AlN templates due to the decreased lattice mismatch, resulting in higher crystal quality and shortening the radiative lifetime (from 280 to 227 μs) related to 5D4–7FJ (J = 3, 4, 5, 6) transitions in Tb3+ ions. Through color filters, RGB emissions originating from the respective transitions are selectively obtained at the same light-emitting area. The multi-color AlxGa1−xN:Tb-based LEDs would be a novel light source for wide applications such as micro-LED displays.

Nanostructured surfaces found in nature offer powerful strategies for thermal-fluid manipulation, yet their replication into durable engineered materials is constrained by fabrication limitations and a lack of comprehensive performance testing. We optimized a dissolvable nanoimprint lithography technique by combining it with pulse electrodeposition to create a repeatable, high-fidelity nanoscale replication method that transfers cicada wing nanopillars onto copper surfaces with >95% geometric fidelity. The resulting nanostructured metal surfaces achieved near cicada wing superhydrophobicity after silane modification and exhibit markedly enhanced pool-boiling heat transfer performance, with a 200% increase in critical heat flux compared to smooth copper samples. This work provides a versatile protocol for exploring nanoscale structure–function relationships and advancing high-efficiency cooling technologies.

Reconfigurable field-effect transistors (RFETs) based on ambipolar two-dimensional (2D) semiconductors provide a versatile platform for multifunctional logic and neuromorphic computing. Traditional RFET architectures typically rely on horizontally arranged multi-gate structures to create tunable homojunctions, a design that imposes significant constraints on lateral scaling due to the required physical gaps between adjacent gates. In this work, we report a reconfigurable WSe2 transistor that achieves polarity control through a complementary electrostatic shielding mechanism. By employing an asymmetric contact configuration consisting of a top-contacted source and a bottom-contacted drain, we demonstrate that these electrodes can selectively shield the top-gate and back-gate fields, respectively. This architecture ensures that the back gate independently modulates carrier injection at the source junction while the top gate governs injection at the drain junction. Such a vertically decoupled dual-gating scheme enables a single device to exhibit robust reconfigurable n- and p-type characteristics with a scaled lateral channel length of ∼500 nm, which is a notable improvement over conventional split-gate RFETs based on 2D materials (∼2 μm). Furthermore, we demonstrate a complementary logic inverter based on this device that achieves a static power consumption below 10 pW. This study introduces a novel physical principle for RFET operation and offers a promising pathway for the continuous scaling of reconfigurable 2D electronics.

We demonstrate a precursor-modulation growth scheme to overcome the efficiency limitations of ultraviolet-A (UVA) light emitting diodes (LEDs) caused by interface intermixing and poor carrier confinement. By incorporating intentional growth interruptions, we engineered more abrupt interfaces with Al-rich interfacial “spikes.” Scanning transmission electron microscopy energy-dispersive x-ray spectroscopy mapping and Schrödinger–Poisson simulations confirm these spikes increase conduction- and valence-band offsets by over 50%, improving electron–hole wavefunction overlap by approximately 20%. The resulting 380-nm micro-LEDs achieved a peak external quantum efficiency of 41%. Notably, the devices maintain high efficiency above 40% up to a current density of 200 A/cm2 with negligible droop. This approach provides a scalable and robust pathway for high-power, high-efficiency solid-state UVA emitters.

In this work, we report on recent results in understanding and addressing the issue of interface smearing in high-aluminum content AlGaN/AlGaN heterostructures. On the one hand, the growth of high-crystal quality AlGaN by metal–organic vapor phase epitaxy requires the use of high temperatures, but, on the other hand, this may lead to alloy intermixing between barrier and channel layers, which smoothens out the polarization contrast and severely degrades or even completely destroys the 2-dimensional electron gas (2DEG). We show that x-ray diffraction analysis can be used as a nondestructive way to assess the sharpness of the interface, and that improved growth schemes can be successfully used to achieve high-quality 2DEG, as confirmed by contactless resistivity measurements. In particular, sheet resistivities around 2500 Ω/□ were demonstrated for AlN/Al0.75Ga0.25N, consistent with the best-reported values in the literature.

Homogeneous p–n junctions in two-dimensional transition metal dichalcogenides (e.g., MoS2) demonstrate significant potential in high-performance optoelectronic devices. However, achieving stable and controllable p-type doping in MoS2 remains challenging, hindering the construction of high-quality p–n homojunctions. Traditional doping methods such as chemical adsorption or gate voltage modulation often suffer from issues like poor stability or complex fabrication processes. This study revealed that oxygen plasma treatment effectively modulated the surface morphology and potential of two-dimensional perovskite (2DPVK) nanosheets grown by a floating solution growth method. Furthermore, by establishing a van der Waals interface between processed 2DPVK and MoS2, successful reconfiguration of carrier polarity in MoS2 was achieved. This enabled the fabrication of lateral MoS2 homogeneous p–n junctions by spatially selective treatment of 2DPVK. The homojunction device exhibited pronounced rectification characteristics and maintained a low dark current. Under laser illumination, the photocurrent increased by four orders of magnitude relative to the dark current, and the open-circuit voltage reached 0.6 V. Photocurrent mapping further revealed the dominant role of the built-in electric field in carrier separation. In the self-driven (zero bias) mode, the device demonstrates a high responsivity of 0.33 A W−1. This study successfully achieved selective p-type doping of MoS2 through interface-engineered van der Waals stacking, which provides innovative insights for controllable design in high-efficiency optoelectronic devices based on two-dimensional materials.

We demonstrate that the viscoelastic evolution during mist chemical vapor deposition (mist-CVD) of amorphous TiOx (a-TiOx) is governed by near-surface-weighted non-equilibrium transitions rather than spatially uniform processes. Using dual-frequency quartz crystal microbalance (QCM) measurements at 9 and 27 MHz, we show that higher-frequency data resolve discrete viscoelastic regimes that remain hidden in conventional depth-averaged measurements. To enhance analytical reliability, the characteristic relaxation time τ was extracted via a unified exponential fitting protocol with residual-based uncertainty estimation. Arrhenius analysis with error bars reveals a clear deviation from linearity, indicating that the relaxation cannot be described by a single activation energy. This non-Arrhenius behavior is further supported by the lognormal distribution of τ and its correlation with the viscoelastic slope parameter S, demonstrating the coexistence of multiple relaxation pathways. These findings establish multi-frequency QCM as a statistically robust, depth-selective probe for investigating near-surface-weighted non-equilibrium dynamics during solution-derived oxide growth.

The electronic transport properties of carbon nanotubes (CNTs) are strongly affected by their surrounding environment, making the underlying substrate a critical factor for device performance. Here, we demonstrate enhanced carrier transport of individual single-walled CNTs on hexagonal boron nitride (hBN) by directly comparing CNT channels on SiO2 and hBN within the same nanotube. This within-tube comparison removes tube-to-tube variability in chirality, diameter, and defect density, allowing the intrinsic substrate effect to be evaluated more reliably. The CNTs were synthesized using gas flow-directed growth, which yields long, well-aligned CNTs without transfer processes, allowing a single nanotube to extend across different substrate regions. Multichannel field-effect transistors fabricated along an individual CNT exhibit clear ambipolar characteristics. CNT channels on hBN consistently exhibit higher field-effect mobility than those on SiO2. In contrast, temperature-dependent transport near the charge neutrality point exhibits thermally activated behavior with similar activation energies (15–20 meV) on both substrates, indicating that the intrinsic small bandgap of CNTs is largely unaffected by the substrate. These results provide direct evidence that hBN enhances low-field carrier transport in CNTs and establish a foundation for the fabrication of high-performance electronics based on hBN-supported CNTs.

We propose a method using a superconducting nanostrip single-photon detector (SNSPD) that can significantly reduce resolution compared with conventional imaging detectors. An SNSPD is advantageous for miniaturization because it consists of a single superconducting strip and allows the direct detection of hard x rays when a thick superconductor with a high atomic number is utilized. A two-dimensional image can be obtained by arranging superconducting strips in a one-dimensional array, rotating the detector or sample, and reconstructing the image using computed tomography technology. One-dimensional SNSPD arrays made of tantalum nitride with a pitch of 100 nm, corresponding to the resolution, were fabricated. A prototype detector was assembled using a counter located at room temperature, incorporating flexible printed circuits with 100 signal cables connected the SNSPD array to the counter via a relay connector to dissipate heat at room temperature. It was demonstrated that the heat flow to the SNSPD array and the signal loss during x-ray detection could be effectively suppressed. By simultaneously obtaining x-ray detection signals from two adjacent strips, it was observed that crosstalk occurred; however, increasing the film thickness helped reduce the occurrence of crosstalk. For strips with a thickness of 270 nm, the crosstalk occurrence rate was approximately 35%, which was deemed acceptable. We conclude that a resolution of 100 nm for hard x rays can be achieved using the SNSPD array.

High-throughput (HT) and automated fabrication methodologies are transforming the development of thin film organic optoelectronic devices. Organic semiconductor materials typically exhibit morphology-dependent performance, and their integration into lab-scale automated systems and roll-to-roll workflows would benefit from non-destructive, rapid, and reliable characterization tools. Distinguishing vertical segregation and microstructural evolution during processing remains a major challenge for in-line quality control and materials screening. In this work, we evaluate the sensitivity of variable angle spectroscopic ellipsometry (VASE) as a fast and non-invasive technique to monitor vertical microstructure stratification in organic semiconductor thin films based on polymer donor/non-fullerene acceptor bilayers (BLs) using two common materials for photovoltaic applications. We deduce the optical properties of the reference materials using standard critical point and Tauc–Lorentz models and then analyze model BL samples with donor/acceptor interfaces before and after thermal annealing. The ellipsometric response suggests that the technique can distinguish with high accuracy sharp BL interfaces and vertically separated blends. The findings in this work demonstrate that VASE can serve as an effective HT diagnostic tool for tracking layer dynamics in automated fabrication environments, providing a valuable bridge between process control and device optimization.

Thin-film surface acoustic wave (TF-SAW) phononic crystals (PnCs) are promising for manipulating gigahertz acoustic waves, but achieving wide bandgaps at high frequencies remains challenging because achieving them requires both strong acoustic confinement and efficient periodic modulation. Here, we demonstrate high-frequency TF-SAW PnCs on a LiTaO3/SiC platform and realize ultra-wide Love-mode bandgaps in the gigahertz regime. Using a 200-nm-thick 42°YX-cut LiTaO3 thin film on SiC, we systematically investigate two representative geometries: a two-dimensional triangular lattice of etched air holes and a one-dimensional groove array. Transmission-line measurements confirm pronounced suppression of Love-mode propagation over 2.64–3.31 GHz (22.5%) for the triangular-lattice PnC and 2.50–3.29 GHz (27.3%) for the 1D groove PnC, in agreement with the calculated band structures. We further clarify the geometric design trends governing the bandgap characteristics and identify deeper etching together with reduced lattice period as practical routes toward even wider bandgaps and higher operating frequencies. These results establish LiTaO3/SiC TF-SAW PnCs as a compelling platform for high-frequency, wideband acoustic wave manipulation and highlight their strong potential for next-generation integrated acoustic devices, including filters, resonators, and sensors.

We present measurements of thermal conductivity and thermal boundary conductance (TBC) in the layered crystal BiOI. These measurements are applied to bulk crystals and crystalline films grown at low temperature (623 K) using chemical vapor methods. Such low-temperature growth was enabled by the growth kinetics of halogens in a reduced oxygen environment. The temperature-dependent Raman spectra showed red shifts of −8 × 10−3 and −12 × 10−3 cm−1 K−1for the characteristic A1g peak of the bulk and film samples, respectively. Most peaks also showed broadening with increased temperature, which indicated that phonon lifetimes are limited by anharmonic scattering. Laser heating measurements were combined with thermal models based on the finite-element method to estimate a directionally averaged thermal conductivity of 1.1 W m−1 K−1 in the bulk crystal. This low thermal conductivity was investigated by computing the phonon dispersion from first principles, which revealed extreme hybridization between acoustic and optical modes that is uncommon for layered crystals. The TBC of an exfoliated film and a grown film were measured to be 17 × 106 and 10 × 106 W m−2 K−1, which are at the lower end of solid–solid interfaces at room temperature. These measurements are valuable for applications in thermal isolation and understanding the thermal limits of BiOI electron devices given its semiconducting nature and low-temperature growth that is compatible with three-dimensional integration of electronics.

Red emission remains a major bottleneck for practical full-color micro-light-emitting diodes (microLEDs) because the quantum efficiencies of InGaN decrease in the long-wavelength region. To enhance red emission, this study developed a honeycomb-latticed InGaN/GaN nanocolumn array integrated with an Ag-based plasmonic LED structure. Finite-difference time-domain simulations were used to optimize the lattice parameters, identifying a = 220 nm and D = 190 nm as the optimal geometries. This design provided an electric-field enhancement of approximately 4.5 at λ = 623 nm, indicating strong surface plasmon polariton coupling in the red region. A device fabricated with the same parameters exhibited up to a 6.3-fold photoluminescence enhancement under surface excitation, outperforming the 5.9-fold enhancement previously achieved under backside excitation. These results demonstrate that honeycomb-latticed plasmonic engineering is effective for boosting red emission in InGaN-based structures and offers a promising route to high-efficiency red microLEDs.

This study examines the nature of current contrast formation and local transport mechanisms during scanning spreading resistance microscopy (SSRM) investigation of an undoped InAs/GaSb heterostructure. We demonstrate that in the high contact force regime (>100 nN), which is essential for stable visualization of layers on the cleaved cross section of the structure, an anomalous current signal distribution emerges. The current from GaSb layers significantly exceeds that from InAs layers. Based on a combination of SSRM data with numerical modeling of the carrier distribution within the layers, we demonstrate that the observed contrast is predominantly determined by contact resistance (Rc) rather than spreading resistance (Rs). This phenomenon is interpreted within a model in which the high local pressure at the nanocontact induces a compressively strained shell. This highly deformed region generates a high, steep potential barrier that suppresses interband electron tunneling at the diamond tip–InAs interface. Conversely, the GaSb valence band structure preserves a quasi-metallic hole transport path. Our results indicate the decisive role of tip-induced band structure modification during the nanoscale electrical characterization of narrow-gap materials.

Hyperspectral imaging enables simultaneous acquisition of spatial and spectral information and plays a key role in material identification and compositional analysis. However, existing camera-based hyperspectral imaging systems are constrained by detector materials and spectral acquisition schemes, making it challenging to achieve broadband coverage and high spectral resolution. This limitation restricts their application in scenarios requiring high spectral accuracy and broadband spectral analysis. In this work, we propose a hyperspectral single-pixel imaging approach that realizes high spatial and spectral resolution imaging from 371 to 1725 nm. The proposed method takes advantage of the complementary angular reflection states of a digital micromirror device to partition the modulated visible and short-wave infrared light into two physically separated optical channels, each coupled to an independent spectral detection module. The system achieves spectral resolutions of 1.1 nm in the visible band and 3.3 nm in the short-wave infrared band and reconstructs a 128 × 128 × 770 hyperspectral data cube. Moreover, acceptable reconstruction is achieved at sampling ratios as low as 10% using compressive sensing. Imaging experiments on various samples validate the performance of the system and demonstrate its potential for industrial inspection and biomedical analysis.

The nanoscale air channel photodiode (NACPD) is an emerging device that combines the advantages of vacuum phototubes and semiconductor photodiodes. Its ballistic transport mechanism theoretically enables high-speed operation and high radiation hardness. However, the irradiation performance of NACPDs has not yet been fully investigated. This study investigates the effects of gamma and neutron irradiation on the performance of InGaAs NACPDs. Experimental results show that gamma irradiation has a more pronounced impact on the dark current than neutron irradiation. After exposure to 100 krad(Si) gamma radiation at a dose rate of 10 rad(Si)/s, the dark current increased by approximately 40%. In contrast, the dark current remains largely unchanged following 1.2 MeV neutron irradiation up to a fluence of 5 × 1011 n/cm2. Both gamma and neutron irradiations have minimal influence on the photocurrent, with variations remaining below 10%, and devices exhibited stable performance before and after irradiation. These findings indicate that InGaAs NACPDs possess exceptional radiation tolerance, making them promising for photodetection and sensing applications in space missions and nuclear power environments.

We demonstrate a spectral-focusing coherent anti-Stokes Raman scattering (SF-CARS) spectroscopy system driven by a single all-fiber gain-managed nonlinear amplification laser. By exploiting the synergistic interplay between self-phase modulation and normal group-velocity dispersion in the gain fiber, the source directly delivers spectrally broadened pulses with an intrinsically linear chirp (pulse energy >100 nJ), eliminating external pulse stretchers and chirp-matching optics. Leveraging the intrinsic delay–frequency mapping, we achieve broadband SF-CARS detection covering a significant portion of the fingerprint region (500–1200 cm−1) with a spectral resolution of ∼13 cm−1. The system capability for sensitive and multiplex chemical analysis is validated by measurements of gaseous SF6 and liquid mixtures of benzene and DMSO. These results establish a compact, robust excitation architecture that advances SF-CARS toward turn-key coherent Raman spectroscopy and high-speed multi-component imaging.

Diffraction of a surface spin wave by a through hole formed inside the in-plane magnetized yttrium iron garnet (YIG) film is investigated both experimentally and theoretically for the case where the hole diameter is significantly smaller than the wavelength. The study reveals a super-resolution and super-directional propagation phenomenon characterized by the formation of a distinct shadow trace from the hole in the spin-wave profile. This shadow is elongated at a long distance from the hole. This occurs along the directions of super-directional wave propagation, corresponding to the inflection points of the isofrequency curve. Theoretical predictions show excellent agreement with experimental observations of super-directional magnon beams engineered by anisotropic dispersion in YIG and are further validated by micromagnetic simulations. The observed formation and splitting of spin-wave beams, along with the extended non-diffracted beam propagation distance, highlight the potential application of these effects in spin-wave multiplexers for magnonic logic devices.

Plasmonic metasurfaces can achieve static structural colors with high resolution, high efficiency, high saturation, and a wide color gamut. Integrating phase change materials and electro-optical components into metasurfaces can further achieve dynamically adjustable structural colors. However, it remains challenging to build a platform with independent control of the basic structural color attributes [HSB (hue, saturation, and brightness)] and dynamic polarization response. Here, we demonstrate a plasmonic metasurface based on an anisotropic Al nanopillar array and achieve independent control over the hue, saturation, and brightness of the structural colors through the geometric parameters of the nanopillar array. It is also shown that dynamic color adjustability can be achieved by adjusting the angles of the polarizer and the analyzer. Our scheme provides a simple method for achieving three-dimensional HSB color control and polarization-driven dynamic response in structural colors. This greatly enhances the information capacity and flexibility of optical metasurfaces in fields such as high-density displays and optical encryption.

The development of high-resolution, miniaturized, and cost-effective spectrometers remains a critical technical challenge. In this work, we demonstrate a high-resolution computational spectrometer by exploiting the chaotic effects induced in side-polished multimode fibers (MMFs). The polishing breaks the structural symmetry of the circular fiber, thereby efficiently exciting guided modes and causing chaos. By forming a 5-cm-long polished region, a spectral resolution of ∼0.5 nm is achieved, representing a one-third improvement over an unpolished MMF of the same length. Moreover, we develop a spectral reconstruction algorithm that integrates adaptive regularization and the Savitzky–Golay filter, enabling real-time reconstruction with enhanced accuracy and robustness. Compared to the Tikhonov regularization algorithm alone, the proposed method reduces the reconstruction error by 50%. This scheme, which leverages chaotic effects to enhance spectral resolution, offers an effective design strategy for developing high-resolution spectrometers.

Flexoelectricity, driven by strain gradients, offers a mechanical route to manipulate ferroelectric polarization and electronic states for nanoscale applications. In this work, we demonstrate topography-induced flexoelectric engineering to modulate the energy band structure of the MoS2/CuInP2S6 (CIPS) heterostructure for high-performance optoelectronics. By deforming CIPS flakes over designed topographical variations, controlled strain gradients can be induced to pin the ferroelectric polarization via a flexoelectric potential field. This locally defined polarization serves as an effective modulation for the MoS2 band structure. By utilizing a nanowire to induce local curvature, a potential barrier is created in the MoS2 channel without requiring doping or electrostatic gating, which suppresses thermally excited carriers while simultaneously promoting the separation of photogenerated carriers. The curved MoS2/CIPS photodetector exhibits a significant performance enhancement. Under 450 nm illumination, the responsivity increases from 0.93 to 4.74 A/W, and the specific detectivity reaches 2.22 × 1012 Jones, a tenfold enhancement over regular devices. These results establish a direct link between topography-controlled flexoelectric modulation and device functionality, providing a versatile route for designing energy landscapes for 2D devices.

The in-sensor computing paradigm, which enables rapid signal processing with low energy consumption, pursues a frontier model to reduce data transmission and redundancy. The direct conversion of light signals into photocurrent is achieved in multiferroic photodetectors, which implement in-sensor computing. The millisecond response and detectivity of ∼1015 Jones enable pronounced performance in wavelengths 300–430 nm. By leveraging the plastic photocurrent/photoconductance, Bi4Ti3−xFexO12 multiferroic photodetectors exhibit memory/forgetting and logic functions (OR, AND, and NOT) under light and electric pulse stimulation, which is attributed to the coupling of magnetic photocurrent with the imprinting effect. The observations highlight the advantages of in-sensor memory and computing.

We report a quantitative decoupling of carrier concentration and mobility in graphene oxide (GO)-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and identify the dominant transport factor associated with electroluminescence (EL) efficiency in polymer light-emitting diodes. Combined Hall-effect and space-charge-limited current analyses reveal no systematic correlation between carrier concentration and device performance, whereas hole mobility exhibits a pronounced maximum at an optimal GO loading and closely follows the EL efficiency trend. This non-monotonic behavior is attributed to the competition between improved percolation pathways and disorder-induced carrier scattering. Despite minor variations in optical transmittance and work function, device performance is significantly improved, supporting the dominant role of effective vertical transport in device operation. GO incorporation optimizes effective injection/transport pathways and facilitates field-assisted hole transport into the emissive layer, which may contribute to more favorable recombination conditions. The optimized device achieves a maximum luminance of 3910 cd/m2 and a current efficiency of 2.48 cd/A, corresponding to an order-of-magnitude enhancement. These results establish mobility-governed effective vertical transport as a key mechanism and provide a physically grounded design principle for optimizing PEDOT:PSS-based optoelectronic devices.

An ultrasensitive optical DNA biosensor based on magnesium oxide (MgO) nanoparticles is reported for the detection of Salmonella typhimurium. The sensing mechanism relies on photoluminescence (PL) modulation governed by defect-mediated charge transfer interactions known as photoinduced electron transfer upon DNA hybridization. The MgO nanostructures exhibit strong emission centered at ∼780 nm, which is significantly enhanced upon probe DNA immobilization due to surface defect passivation. Subsequent hybridization with target DNA induces concentration-dependent PL quenching, enabling quantitative detection in the range of 30–150 aM. A linear calibration response with a high correlation coefficient (R2 = 0.96) is obtained, yielding a limit of detection of 4.2 aM. The biosensor demonstrates excellent specificity, with a ∼6.5-fold higher response for complementary DNA compared to non-complementary sequences. The observed PL modulation is attributed to radiative recombination suppression via charge transfer interactions following dsDNA formation. The developed platform offers a rapid, label-free, and highly sensitive approach for pathogen detection, highlighting the potential of MgO-based optical biosensors for advanced diagnostic applications.

Laser power converters (LPCs) are key components in laser wireless power transmission systems. In this work, accelerated lifetime tests were conducted on GaAs single-junction and InGaAs single-junction LPCs by elevating the device temperature to 160, 175, and 190 °C to induce accelerated aging. Dark current injections of 8.06 and 8.62 A were applied to GaAs and InGaAs LPCs, respectively, corresponding to simulated photocurrent under laser power densities of 14.65 and 12.78 W/cm2. The failure distributions were fitted using the Arrhenius model, yielding activation energies of 1.11 eV for GaAs single-junction LPCs and 1.15 eV for InGaAs single-junction LPCs. The estimated lifetimes of both devices under an operating temperature of 85 °C are approximately 64 years. Post-aging characterization reveals that device degradation is mainly caused by an increase in series resistance, which leads to a reduction in fill factor and maximum power point. The increase in series resistance is attributed to the degradation of grid electrodes. In addition, the formation of surface cracks is likely associated with the curvature of the LPC exceeding its strain limit.