Conversion Efficiency Research Articles

Lattice Strain Regulation and Halogen Vacancies Passivation Enable High-Performance Formamidine-Based Perovskite Solar Cells.

Formamidinium lead iodide (FAPbI3) perovskite has lately surfaced as the preferred contender for highly proficient and robust perovskite solar cells (PSCs), owing to its favorable bandgap and superior thermal stability. Nevertheless, volatilization and migration of iodide ions (I-) result in non-radiating recombination centers, and the presence of large formamidine (FA) cations tends to cause lattice strain, thereby reducing the power conversion efficiency (PCE) and stability of PSCs. To solve these problems, the lead formate (PbFa) is added into the perovskite solution, which effectively mitigates the halogen vacancy and provides tensile strain outside the perovskite lattice, thereby enhancing its properties. The strong coordination between the C═O of HCOO- and Pb-I backbones effectively immobilizes anions, significantly increases the energy barrier for anion vacancy formation and migration, and reduces the risk of lead ion (Pb2+) leakage, thereby improving the operation and environmental safety of the device. Consequently, the champion PCE of devices with Ag electrodes can be increased from 22.15% to 24.32%. The unencapsulated PSCs can still maintain 90% of the original PCE even be stored in an N2 atmosphere for 1440h. Moreover, the target devices have significantly improved performance in terms of light exposure, heat, or humidity.

Achieving 19.4% Efficiency Polymer Solar Cells by Reducing Backbone Disorder in Donor Terpolymers

AbstractThe ternary copolymerization strategy has emerged as a promising strategy for developing high‐efficiency donor polymers in polymer solar cells (PSCs). Terpolymers based on the star polymer PM6 have already realized good photovoltaic performance. However, challenges such as the intricate synthesis of fluorine‐substituted benzodithiophene (F‐BDT) unit of PM6 and entropy increase induced by backbone disorder have hindered the construction of high‐performance donor terpolymers. In this work, these challenges are addressed by opting for the cost‐effective chlorinated‐substituted benzodithiophene unit (Cl‐BDT) as an alternative to F‐BDT and incorporating the large dipole moment and electron‐deficient TPD group as the third component into the high‐performance donor polymer of PM7. As expected, this approach effectively suppresses terpolymer backbone disorder while enhancing crystallinity, thereby optimizing morphology and improving charge generation and transport. Remarkably, the PM7‐TPD‐10‐based device with 10% TPD replacement achieves a champion power conversion efficiency (PCE) of 18.26%. After introducing PM7‐TPD‐10 as the third component into D18:L8‐BO blend, a dual mechanism for improving the efficiency to 19.40% is realized. This work demonstrates that the high dipole moiety as the third component to construct terpolymers is an important strategy to suppress the backbone disorder and increase the crystallinity, facilitating the optimization of morphology and device performance.

Bithieno[3,4-c]pyrrole-4,6-dione-Based Wide-Bandgap Donor Polymers for Efficient Polymer Solar Cells.

The polymer solar cells (PSCs) have garnered substantial interest owing to their lightweight, cost-effectiveness, and flexibility, making them ideal for large-scale roll-to-roll manufacturing. In this study, two wide-bandgap (WBG) donor polymers, PFBiTPD and PClBiTPD, utilizing bithieno[3,4-c]pyrrole-4,6-dione (BiTPD) as the electron-accepting unit and fluorinated/chlorinated benzo[1,2-b:4,5-b']dithiophene (BDT) as the electron-donating moiety are designed and synthesized. The polymers demonstrated large optical bandgaps (exceeding 1.80eV) and are blended with ITIC-4F to form the active layers in PSCs. The PFBiTPD-based devices showed a well-dispersed fibrillar network, facilitating efficient charge generation and transport. Thus, these devices attained a power conversion efficiency (PCE) of 8.60%, featuring a fill factor (FF) of 62.89%, an open-circuit voltage (Voc) of 0.88V and a short-circuit current density (Jsc) of 15.54mA cm-2. In contrast, PClBiTPD-based devices displayed lower performance due to less favorable morphology. The study underscores the importance of polymer design and morphology control in optimizing the photovoltaic performance of PSCs.

Synthesis and characterization of novel double perovskite K2AgBiBr6

Over the past few years, Lead-free halide double perovskites have attracted a tremendous attention such that it is demonstrated by the power conversion efficiency's sharp increase of over 25 %. It has also stimulated a widespread application of halide metal perovskites in other fields, such as light-emitting diodes, field-effect transistors, detectors, and lasers. Double perovskites have been put forth as an alternative to hybrid lead halide perovskites in the last decade because of their efficiency in doing away with the existing toxicity and instability. It is probably the first attempt, to date, that lead-free halide double perovskite K2AgBiBr6 has been made with a cheap, easy-to-use solution-state reaction method. To determine their structure, single crystal X-ray diffraction and PXRD analysis have been employed. The synthesized K2AgBiBr6 adopts the cubic structure with Fm‾3m symmetry and lattice parameters of a = 6.606 (9) Å at room temperature, according to the diffraction result. Energy dispersive X-ray spectroscopy (EDX), elemental mapping, and scanning electron microscopy (SEM) have all been employed to analyze the morphology and elemental composition. Elements including K, Bi, Ag, and Br have been confirmed to be present in the synthesized sample by the EDX technique. For K2AgBiBr6, the 2.859 eV (indirect) and 3.076 eV (direct) bandgaps have been estimated by employing the UV–Vis absorption spectra. Furthermore, the K2AgBiBr6 double perovskite nanocrystal's thermogravimetric analysis/differential thermal and differential scanning analysis (TG/DTA and DSC) curves at 20–800 °C have been measured. An analysis has been conducted on the mechanism of thermal decomposition of synthesized double perovskite. This work demonstrates great promise for future band gap engineering-based photovoltaic and other optoelectronic applications, and it offers a novel path to obtaining premium K2AgBiBr6 double perovskite.

Pressure-Induced Enhancement in Chemical Looping Reforming of CH4: A Thermodynamic Analysis with Fe-Based Oxygen Carriers.

Chemical looping reforming of methane (CLRM) with Fe-based oxygen carriers is widely acknowledged as an environmentally friendly and cost-effective approach for syngas production, however, sintering-caused deactivate of oxygen carriers at elevated temperatures of above 900 °C is a longstanding issue restricting the development of CLRM. Here, in order to reduce the reaction temperature without compromising the chemical-looping CH4 conversion efficiency, we proposed a novel operation scheme of CLRM by manipulating the reaction pressure to shift the equilibrium of CH4 partial oxidation towards the forward direction based on the Le Chatelier's principle. The results from thermodynamic simulations showed that, at a fixed reaction temperature, the reduction in pressure led to the increase in CH4 conversion, H2 and CO selectivity, as well as carbon deposition rate of all investigated oxygen carriers. The pressure-negative CLRM with Fe3O4, Fe2O3 and MgFe2O4 could reduce the reaction temperature to below 700 °C on the premise of a satisfactory CLRM performance. In a comprehensive consideration of the CLRM performance, energy consumption, and CH4 requirement, NiFe2O4 was the Fe-based OCs best available for pressure-negative CLRM, especially for an excellent syngas yield of 23.08 mmol/gOC. This study offered a new strategy to address sintering-caused deactivation of materials in chemical looping from the reaction thermodynamics point of view.

Utilization of Polycyclic Aromatic Solid Additives for Morphology and Thermal Stability Enhancement in Photoactive Layers of Organic Solar Cells.

Volatile solid additives have emerged as a promising strategy for enhancing film morphology and promoting the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a series of novel polycyclic aromatic additives with analogous chemical structures, including fluorene (FL), dibenzothiophene (DBT), and dibenzofuran (DBF) derived from crude oils, are presented and incorporated into OSCs. All these additives exhibit strong interactions with the electron-deficient terminal groups of L8-BO within thebulk-heterojunction OSCs. Moreover, they demonstrate significant sublimation during thermal annealing, leading to increase free volumes for the rearrangement and recrystallization of L8-BO. This phenomenon leads to an improved film morphology and an elevated glass-transition temperature of the photoactive layers. Consequently, the PCE of the PM6:L8-BO blend has been boosted from 16.60% to 18.60% with 40 wt% DBF additives, with a champion PCE of 19.11% achieved for ternary PM6:L8-BO:BTP-eC9 OSCs. Furthermore, the prolonged shelf and thermal stability have been observed in OSCs with these additives. This study emphasizes the synergic effect of volatile solid additives on the performance and thermal stability of OSCs, highlighting their potential for advancing the field of photovoltaics.

A highly sensitive dual-mode lateral flow immunoassay based on plasmonic hollow Ag/Au nanostars enhancing light absorption

The conventional lateral flow immunoassay (LFIA) based on gold nanoparticles (Au NPs) is limited by low sensitivity due to the insufficient brightness of Au NPs. To address this problem, noble metal nanomaterials with localized surface plasmon resonance (LSPR) and synthetic tunability are potential signal outputs for LFIA, which can achieve better optical properties by adjusting the preparation conditions. Herein, this study prepared the hollow silver/gold nano-stars (HAg/Au NSts) as LFIA signal output via the galvanic replacement method. HAg/Au NSts with anisotropic hollow alloy nanostructures exhibit a wide visible light absorption band and great NIR thermal conversion efficiency (η = 37.32 %), which endows them with enhanced colorimetric and photothermal signals. Further, we constructed a colorimetric-photothermal (CM-PT) dual-signal HAg/Au NSts-LFIA and chose staphylococcal enterotoxin B as the target analyte. The linear range of HAg/Au NSts-LFIA is 0.19–100 ng mL−1, and the limit of detection (LOD) is up to 0.29 ng mL−1 and 0.09 ng mL−1 in the colorimetric and photothermal modes respectively. Compared with the conventional Au NPs-LFIA, HAg/Au NSts-CM/PT-LFIA effectively improved the detection performance of LFIA. In addition, HAg/Au NSts-LFIA also showed satisfactory sensitivity (vLOD = 0.78 ng mL−1) and recovery (89.06–114.74 %) in milk and pork samples. Therefore, this work provides a new shape design idea for noble metal nanomaterials in biosensor applications.

Efficient and stable perovskite mini-module via high-quality homogeneous perovskite crystallization and improved interconnect

The efficiency and stability of perovskite module devices are mainly limited by the quality of scalable perovskite films and sub-cells’ lateral contact. Here, firstly, we report constant low temperature substrate to regulate the growth of perovskite intermediate films to slow down the crystallization for obtaining high-quality homogeneous perovskite films in large scale size, which avoid the effect of the ambient temperature on the film quality. Secondly, a scribing step named P1.5 was added before the top function layers deposition, the diffusion barrier layer can be formed “naturally” at the interconnection interface without introducing any additional materials, which well alleviates the diffusion degradation process. As a result, our inverted perovskite devices exhibit a very small efficiency loss with area expansion comparable to other photovoltaic devices (for example, Cadmium Telluride), the perovskite module (aperture area 14.61 cm2) shows a certified quasi-steady-state power conversion efficiency of 22.73%, and the module maintaining over 90% of its initial efficiency after 1000 hours of continuous operation under illumination.

Reprogramming the myocardial infarction microenvironment with melanin-based composite nanomedicines in mice

Myocardial infarction (MI) has a 5-year mortality rate of more than 50% due to the lack of effective treatments. Interactions between cardiomyocytes and the MI microenvironment (MIM) can determine the progression and fate of infarcted myocardial tissue. Here, a specially designed Melanin-based composite nanomedicines (MCN) is developed to effectively treat MI by reprogramming the MIM. MCN is a nanocomposite composed of polydopamine (P), Prussian blue (PB) and cerium oxide (CexOy) with a Mayuan-like structure, which reprogramming the MIM by the efficient conversion of detrimental substances (H+, reactive oxygen species, and hypoxia) into beneficial status (O2 and H2O). In coronary artery ligation and ischemia reperfusion models of male mice, intravenously injecting MCN specifically targets the damaged area, resulting in restoration of cardiac function. With its promising therapeutic effects, MCN constitutes a new agent for MI treatment and demonstrates potential for clinical application.

High-performance GaN ultraviolet polarization-sensitive photodetector based on ferroelectric polarization LiNbO3

High responsivity ultraviolet (UV) photodetectors (PDs) are essential for abundant civilian and military applications. Gallium nitride (GaN) has emerged as an ideal material for UV PD fabrication due to its favorable properties. However, the quality of GaN epitaxial layers significantly impacts device performance and reliability. Sapphire-based GaN epitaxial growth technology enables the realization of high-quality GaN epitaxial layers, making it the preferred choice for GaN substrates. Nonetheless, the thermal expansion coefficient mismatch between sapphire and GaN can lead to crystal mismatch and stress accumulation at high temperatures, affecting device performance and reliability. In contrast, lithium niobate (LiNbO3) exhibits similar coefficients of thermal expansion to GaN, mitigating crystal mismatch and stress accumulation issues. Here, we report the realization of a GaN UV PD by laminating GaN membrane onto ferroelectric LiNbO3 through selective electrochemical etching of the sapphire-based GaN epitaxial film. The LiNbO3-based GaN PD achieves a specific high on/off ratio of 107. At a 5 V bias voltage, the device exhibits a high peak responsivity of 1.712 × 103 A/W under 325 nm laser illumination. Furthermore, the device demonstrates excellent performance for polarization light detection, with a polarization ratio of approximately 54.95. Exploiting the local ferroelectric polarization of x-cut LiNbO3, the photogenerated electron–hole pairs in GaN are efficiently separated by the electrostatic field from the polarization of ferroelectric LiNbO3, resulting in enhanced light-to-electric conversion efficiency. Our work presents a method for fabricating high responsivity GaN-based UV PD, showcasing the potential of integrating ferroelectric LiNbO3 to enhance device performance.

Molten Salt Synthesis of Ti3C2/Cu Cocatalyst for Enhanced TiO2 Photocatalytic CO2 Reduction

AbstractPhotocatalytic reduction of CO2 is considered as a crucial pathway towards achieving sustainable energy and environmental goals. Nonetheless, attaining efficient CO2 conversion poses significant challenges, primarily due to the slow dynamics of charge carriers and the high activation energy required to break C=O bonds. In this study, a novel strategy involving Lewis acid molten salt etching is investigated to engineer a titanium oxide (TiO2)‐based photocatalysts with dual electron transfer channels (i. e., Ti3C2/Cu), which targets the photoreduction of CO2 to CO and CH4. Thanks to the dual electron transfer channels presented in the cocatalysts (Ti3C2/Cu), in conjunction with the numerous heterogeneous interfaces between TiO2 and the Ti3C2/Cu cocatalysts, this hybrid catalyst not only reduces charge transfer resistance but also accelerates the dynamics of photogenerated charge carriers. Consequently, the TiO2/Ti3C2/Cu hybrid catalyst demonstrates an exceptional photocatalytic CO2 reduction rate of 13.67 μmol g−1 h−1, with a total utilized photoelectron number (UPN) of 102.34 μmol g−1 h−1. which is 3.99‐fold higher than that of unmodified TiO2. This research provides a new approach for the preparation of dual cocatalysts through a one‐step molten salt synthesis process.

Regulation of Electron Delocalization Region in 2D Heteroligand-Based Copper-Organic Framework to Enhance Charge Storage.

The rechargeable aqueous ammonium ion battery shows great potential in low-cost energy storage system because of its long life and environmental friendliness. However, most inorganic host materials used in ammonium ion batteries are still limited by slow diffusion kinetics. Herein, it is identified that a 2D heteroligand-based copper-organic framework featuring numerous ammonium ion adsorption site in the π-conjugated periodic skeleton supplies multiple accessible redox-active sites for high-performance ammonium storage. Benefitting from the effective regulation of electron delocalization by heteroligand and the inherent hydrogen bond cage mechanism between ammonium ions, the resultant full battery delivers a large specific energy density of 211.84Whkg-1, and it can be stably operated for 12000 cycles at 5Ag-1 for over 80 days. This explanatory understanding provides a new idea for the rational design of high-performance MOF-based ammonium ion battery cathode materials for efficient energy storage and conversion in the future.

Enhancing D/A Interactions via Porphyrin Isomerization to Improve Photovoltaic Performance.

The interactions between the electron donors and electron acceptors (D/A) play important roles for the performance of organic solar cells (OSCs).While the isomerization strategy is known to optimize molecular geometries and properties, the impacts of isomerization on the donors or acceptors in D/A interactions have not been extensively investigated.Here in, we innovatively investigated the impacts of donor isomerism on the D/A interactions by synthesizing two small molecule donors m-ph-ZnP2and p-ph-ZnP2by linking two functionalized porphyrins at the meta and para positions of phenyl groups, respectively.Compared with p-ph-ZnP2, m-ph-ZnP2displays reduced self-aggregation but with PC61BM.Consequently, a much higher power conversion efficiency (PCE) of 5.43% is achieved for the m-ph-ZnP2binary OSCs than the p-ph-ZnP2devices with a PCE of 2.03%.The enhanced performance of m-ph-ZnP2-based device can be primarily attributed to the stronger intramolecular charge transfer (ICT), the enhanced D/A interactions, the improved charge transfer, and the suppressed charge recombination.Furthermore, the ternary devices based on m-ph-ZnP2:Y6:PC61BM achieve a PCE of 8.34%. In short, this work elucidates the relationship among the chemical structure, D/A interactions and device performance, providing valuable guidelines for designing efficient OSCs materials.

Supramolecular Cucurbit[5]uril Modulates the Buried SnO2/Perovskite Interface for Efficient and Stable Perovskite Solar Cells

AbstractReducing non‐radiative recombination caused by defects at buried interfaces is crucial to the development of efficient and stable perovskite solar cells (PSCs). Herein, supramolecular cucurbit[5]uril (CB[5]) is introduced into the SnO2 layer, where it engages in host–guest interactions to suppress oxygen vacancies in SnO2, prevent particle aggregation, and enhance the electron mobility of SnO2. By serving as a bridging agent at the buried interface between SnO2 and the perovskite layer, CB[5] reduces the defect density and improves the carrier extraction efficiency. It also reduces the surface energy of the SnO2 substrate, facilitates the formation of large grains in the perovskite film, alleviates residual lattice stresses, and enhances the film quality. Consequently, the PSC with CB[5] shows a champion power conversion efficiency of 24.83%. Moreover, an unencapsulated device incorporating CB[5] retains more than 87% of its initial PCE under continuous illumination at the maximum power point tracking for 1000 h. This study pioneers the utilization of cucurbiturils in PSCs and provides insights into how supramolecular compounds can regulate buried interfaces.

A 3D CFD-FEA co-simulation study of low thermal effusivity TBCs applied to the piston and valves of an SI engine

When applied on combustion chamber walls, thermal barrier coatings (TBCs) with low thermal effusivity provide a pathway for reducing heat transfer and improving SI engine efficiency. A 3D CFD-1D FEA co-simulation routine was employed to study the effects of a proprietary TBC on SI engine performance under different permutations of coating the piston, exhaust valves, and intake valves. Marginal reductions (<0.1% points) in total heat transfer and improvements to efficiency were observed when all the three components were coated with the proprietary TBC. Two hypothetical TBC materials with ideally low thermal effusivities were formed by modifying the current material properties and their effect on engine performance was similarly studied at three engine loads at the same engine speed. It was found that coating all the three components with the lowest thermal effusivity TBC offers the largest improvements (∼0.5% points) in net fuel conversion efficiency accompanied by largest reduction (∼1.1% points) in total heat transfer, thus establishing expectations from future TBC materials.

Grain Manipulation by Annealing Treatment Realizes High-Performance N-Type Bi2Te2.4Se0.6 Thermoelectric Material and Device.

Bi2Te3-based materials play a crucial role in solid cooling and power generation, but the rapidly deteriorated ZT with rising temperatures above 450 K severely limits further applications. Here, this paper reports a novel preparation method of annealing treatment for molten ingot, which can enhance the thermoelectric performance of n-type Bi2Te2.4Se0.6 in a wide temperature range. Instead of conventional halides, copper is adopted to regulate the carrier concentration and grain size to optimal levels. During the process of annealing at 573 K for 4h, the number of twins significantly increases and the grains of Cu-doped samples become larger and more oriented. These optimizations lead to higher carrier mobility with similar carrier concentration compared with the sample without heat treatment. The synergistic effects of Cu doping and annealing treatment realize a high average ZT of 0.89 within 300-600 K in n-type Cu0.02Bi2Te2.4Se0.6. Combined with p-type (Bi,Sb)2Te3, the fabricated thermoelectric device exhibits a high conversion efficiency of 6.9% at a temperature difference of 300 K. This study suggests that annealing treatment is a simple and effective scheme to promote the applications of n-type Bi2(Te,Se)3 in a wide temperature range.

Design considerations of CdSe solar cells for indoor applications under white LED illumination

This work sheds light on the potential of Cadmium Selenide (CdSe) solar cells for indoor applications. CdSe boasts a wide direct bandgap, high carrier mobility, and a high absorption coefficient, making it an attractive candidate for harnessing ambient indoor light. Our study centers around an experimental solar cell architecture composed of FTO/CdSe/PEDOT:PSS/CuI/ITO, which exhibits a power conversion efficiency (PCE) of 6.00 %. Through a meticulous analysis of the core technological aspects of this cell, we successfully replicate the measured current-voltage characteristics and other experimental data, affirming the validity of our simulation modeling approach. Moving forward, we delve into the design and optimization of CdSe-based solar cells under white LED illumination. We emphasize the pivotal role of a double-hole transport layer (HTL) configuration over a single HTL, with a focus on optimizing the alignment between the HTL/back contact and HTL/absorber interfaces. The strategic incorporation of a heavily doped p-type HTL material, boasting both a deep valence band maximum (VBM) and a shallow conduction band minimum (CBM), is identified as paramount, especially for a deep VBM absorber like CdSe. Adding double HTL materials also facilitates efficient hole collection within the CdSe thin film while mitigating undesirable electron-hole recombination at the critical interface between the hole collection layer and the electrode. The implementation of a double HTL configuration based on CuI/ZnTe:Cu or CuI/BCS significantly enhances performance, resulting in a PCE in the order of 20 % under 200 lux and 2900 K LED illumination. Moreover, we introduce the single HTL design to provide other alternatives for efficiency boosting. Upon increasing the work function of the front contact, it is found that the valence band offset between the HTL and the absorber can be engineered, resulting in a PCE above 21.5 %.

Quantum Dot-Based Three-Stack Tandem Near-Infrared-to-Visible Optoelectric Upconversion Devices.

Quantum dots (QDs) exhibit size-tunable optical properties, making them suitable for efficient light-sensing and light-emitting devices. Tandem devices that can convert near-infrared (NIR) to visible (Vis) signals can be fabricated by integrating an NIR-sensing QD device with a Vis electroluminescence (EL) QD device. However, these devices require delicate control of the QD layer during processing to prevent damage to the predeposited QD layers in tandem devices during the subsequent deposition of other functional layers. This has restricted attainable device structures for QD-based upconversion devices. Herein, we present a modular approach for fabricating QD-based optoelectric upconversion devices. This approach involves using NIR QD-absorbing (Abs) and Vis QD-EL units as building modules, both of which feature cross-linked functional layers that exhibit structural tolerance to dissolution during subsequent solution-based processes. Tandem devices are fabricated in both normal (EL unit on Abs unit) and inverted (Abs unit on EL unit) structures using the same set of NIR QD-Abs and Vis QD-EL units stacked in opposite sequences. The tandem device in the normal structure exhibits a high NIR photon-to-Vis-photon conversion efficiency of up to 1.9% in a practical transmissive mode. By extending our modular approach, we also demonstrate a three-stack tandem device that incorporates a single NIR-absorbing unit coupled with two EL units, achieving an even higher conversion efficiency of up to 3.2%.

Bayesian reverse design of high-efficiency perovskite solar cells based on experimental knowledge constraints

To alleviate high costs and lengthy trial-and-error periods associated with traditional optimization methods for perovskite solar cells (PSCs), we developed a data-driven reverse design framework for high-efficiency PSCs. This framework integrates machine learning and Bayesian optimization (BO) to accelerate the optimization process of PSCs by intelligently recommending the most promising parameter configurations for PSCs, such as device structure and fabrication processes. To improve the robustness of the framework, we first designed a two-stage sampling strategy to alleviate the issue of imbalanced dataset classes. Subsequently, by integrating “experimental knowledge constraints” into the BO process, we achieved precise parameter configurations, thus avoiding discrepancies between predicted and actual results due to parameter mismatches. Finally, using SHapley Additive exPlanations, we unveiled key factors influencing the power conversion efficiency (PCE), such as the composition of perovskite solvents. Our framework not only precisely predicted the PCE of PSCs with an area under the curve of 0.861 but also identified the optimal parameter configurations, achieving a high probability of 0.981. This framework offers substantial support for minimizing redundant experiments and characterizations, effectively accelerating the optimization process of PSCs.

Axially-Polarized Excitonic Series and Anisotropic van der Waals Stacked Heterojunction in a Quasi-1D Layered Transition-Metal Trichalcogenide.

Anisotropic optical 2D materials are crucial for achieving multiple-quanta functions within quantum materials, which enables the fabrication of axially polarized electronic and optoelectronic devices. In this work, multiple excitonic emissions owning polarization-sensitive orientations are clearly detected in a multilayered quasi-1D ZrS3 nanoribbon with respect to the nanostripe edge. Four excitons denoted as AS1, AS2, AS, and A2 with E ⊥ b polarized direction and one prominent A1 exciton with E || b polarized emission are simultaneously detected in the polarized micro-photoluminescence (µPL) measurement of 1.9-2.2eV at 10K. In contrast to light emission, polarized micro-thermoreflectance (µTR) measurements are performed to identify the polarization dependence and verify the excitons in the multilayered ZrS3 nanoribbon from the perspective of light absorption. At 10K, a prominent and broadened peak on the lower-energy side, containing an indirect resonant emission (DI) observed by µPL and an indirect defect-bound exciton peak (AInd) observed by both µPL and µTR, is simultaneously detected, confirming the existence of a quasi-direct band edge in ZrS3. A van der Waals stacked p-GaSe/n-ZrS3 heterojunction solar cell is fabricated, which demonstrates a maximum axially-polarized conversion efficiency up to 0.412% as the E || b polarized light incident onto the device.