Search

2D Ruddlesden–Popper perovskites are highly regarded materials for improving the stability of perovskite solar cells (PSCs). Wherein, self‐additive 2D perovskites have recently been proposed to provide substantial strategies for managing the crystallization kinetics and bulk defects. For a profound understanding of the formation mechanisms, herein, with selecting three self‐additive 2D perovskites as demonstrations, a comprehensive analysis of the self‐additive behavior combing experimental and theoretical calculations is conducted. Self‐additive 2D perovskites exhibit more suitable formation energies and strong interaction, which is conducive to realize the self‐additive effect to form more stable structure. As demonstrated, glycine (Gly)‐based spacer cations played a pivotal role in the nucleation and growth of 2D perovskites by adjusting the aggregation state of colloids precursor, resulting in excellent‐quality films with large average grain size (≈3 µm). Meanwhile, theoretical analysis of electronic distribution and binding energies (Eb) revealed that glycine ethyl ester (Gly‐E) perovskite possesses highly robust internal interactions, which will effectively mitigate defect formation and enhance device stability. Endowing with the above outstanding feature, Gly‐E devices exhibited an optimized PCE of 21.60%, one of the highest PCEs among all 2D RP PSCs (n ≤ 6). The findings provide a basis for the rational design of self‐additive 2D perovskites and achieving highly‐performance 2D RP PSCs. [ABSTRACT FROM AUTHOR]

This paper proposes a programmable solar‐powered radio frequency (RF) transmitter. It employs a novel five‐layer structure that effectively integrates solar cells, active circuits, and broadband antenna. This design can directly emit RF signals without the need for additional power supply, enabling efficient energy conversion and transmission. In addition, a U‐shaped coupling line model is introduced to evaluate the performance of the active circuit. We fabricated a sample and measured it. The results of the measurements indicate that the proposed RF transmitter can achieve self‐powering and programmable output at any frequency within the range of 2.08–4.1 GHz, with an output power of no less than 14 dBm. Moreover, the solar cells are placed on both sides of the circuits and antenna for energy harvesting, achieving 100% sunlight insolation with a 75.5% coverage ratio. This design can be used for self‐powered green wireless system applications. [ABSTRACT FROM AUTHOR]

High‐performance flexible photodetectors are urgently demanded for application in many emerging domains including flexible, wearable, portable, and stretchable optoelectronics. In this work, a highly efficient flexible photodetector made of a Ti3C2Tx MXene/pyramidal thin Si heterostructure is successfully fabricated. Thanks to the remarkable light trapping effect as confirmed by numerical modeling based on finite‐element method, the as‐constructed detector demonstrates excellent photoresponse performance in a broadband wavelength spectrum. The optimal responsivity, specific detectivity, and response speed reach ≈530 mA W−1, ≈1.21 × 1012 Jones and 30/14 µs, respectively, at zero bias under near‐infrared light illumination. Specifically, the responsivity is greatly enhanced by ≈2.65 times, as compared with a planar counterpart. In addition, the light detector can maintain its outstanding photoresponse properties upon 1000 cycles of bending test or at diverse bending radii of curvature, owing to its prominent mechanical flexibility and robust bending endurance. Finally, the capability of monitoring the heart rate of a person in a wideband wavelength spectrum and at various bending radii of curvature is presented. The above results imply the huge potential of the flexible light detector for use in some applications such as wearable health monitoring. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (SCs) have gained significant interest in various applications owing to their superior optoelectrical and physical characteristics as compared to polycrystalline films. However, a considerable portion of incident light is typically reflected at the surface of perovskite SCs, leading to insufficient light absorption within the crystal bulk, ultimately resulting in reduced performance of SC‐based photodetectors. In the present work, an inverted pyramid‐shaped structure is in situ introduced on the surface of an MAPbBr3 SC during the crystal growth process, which can reduce light reflection in the surface region and enhance light absorption of the SC. Additionally, the hydrophobic small molecule copper (II) phthalocyanine (CuPc) is thermally evaporated onto the SC, forming a CuPc/MAPbBr3 heterojunction for the first time. The CuPc/pyramid‐shaped MAPbBr3 heterojunction‐based photodetector exhibits self‐powered characteristics and superior optoelectrical performance, achieving a photocurrent of greater than 10−5 A (10−7 A), a responsiveness of 257 mA W−1 (8.84 mA W−1), and a detection rate of 2.98 × 1012 Jones (1.02 × 1011 Jones) at −2 V (0 V) bias. Simultaneously, the device demonstrates excellent long‐term stability under high humidity conditions, retaining 90.5% of its initial photocurrent even after 60 days in a 60–80% humidity environment. [ABSTRACT FROM AUTHOR]

Low‐temperature co‐fired ceramics technology (LTCC) exhibits enormous superiorities in packaging, integration, and interconnection. However, the complex compositions of low‐melting point sintering aids may react with ceramic matrix, which increases the difficulties of phase control and tape casting. In this work, the Li2CO3–B2O3–Bi2O3–SiO2 (LBBS) sintering aid was adopted to sinter ZnZrNb2O8 ceramics with single phase at low temperatures. The LBBS glass could be used to fabricate pure‐phase ZnZrNb2O8 ceramics at a low sintering temperature, promote the grain growth, and increase the densification of ZnZrNb2O8 ceramics. Furthermore, the unit cell volume, NbO6 octahedral distortion, Raman shift, and FWHM changed along with LBBS addition, thereby affecting the microwave dielectric properties. Remarkably, ZnZrNb2O8 ceramics doped with 0.75 wt.% LBBS at 950°C were chemically compatible with the silver electrode and exhibited excellent microwave dielectric characteristics: εr = 27.1, Q × f = 54 500 GHz, and τf = −48.7 ppm/°C, providing candidates for LTCC applications. [ABSTRACT FROM AUTHOR]

Radiative thermal management has attracted increasing attention for the advantages of energy saving and carbon emission reduction. Infrared radiation coatings are widely adopted to alleviate the low infrared emissivity of commonly used metal alloy electrothermal materials. However, traditional infrared radiation coatings are faced with the issues of the unsteady waveband emissivity, low interfacial adhesion to substrates, and poor long‐term thermal stability. Herein, a bush‐shaped vertical graphene (BVG) grown on nichrome (Ni–Cr) wire is demonstrated, relying on which BVG/Ni–Cr wire presents a high blackbody‐like emissivity of ≈0.96 across a wide wavelength range (2.5–18 µm). When used for radiative heating, BVG/Ni–Cr wire achieves a high thermal radiation efficiency with an order of magnitude improvement compared with bare Ni–Cr wire, as well as the superior deformation and thermal stabilities. These findings reveal the impressive potentials of BVG as an excellent infrared radiation material for the energy‐efficient radiative thermal management. [ABSTRACT FROM AUTHOR]

Undesired photoelectronic dormancy through active species decay is adverse to photoactivity enhancement. An insufficient extrinsic driving force leads to ultrafast deep charge trapping and photoactive species depopulation in carbon nitride (g‐C3N4). Excitation of shallow trapping in g‐C3N4 with long‐lived excited states opens up the possibility of pursuing high‐efficiency photocatalysis. Herein, a near‐field‐assisted model is constructed consisting of an In2O3‐cube/g‐C3N4 heterojunction associated with ultrafast photodynamic coupling. This In2O3‐cube‐induced near‐field assistance system provides catalytic "hot areas", efficiently enhances the lifetimes of excited states and shallow trapping in g‐C3N4 and this favors an increased active species density. Optical simulations combined with time‐resolved transient absorption spectroscopy shows there is a built‐in charge transfer and the active species lifetimes are longer in the In2O3‐cube/g‐C3N4 hybrid. Besides these properties, the estimated overpotential and interfacial kinetics of the In2O3‐cube/g‐C3N4 hybrid co‐promotes the liquid phase reaction and also helps in boosting the photocatalytic performance. The photocatalytic results exhibit a tremendous improvement (34‐fold) for visible‐light‐driven hydrogen production. Near‐field‐assisted long‐lived active species and the influences of trap states is a novel finding for enhancing (g‐C3N4)‐based photocatalytic performance. [ABSTRACT FROM AUTHOR]

As the flexible wearable devices are developing rapidly, the requirement for energy storage devices with high energy and power density, excellent flexibility, and high reliability is increasing. Fiber‐shaped supercapacitors offering high power density and excellent flexibility have attracted widespread attention. However, the low energy density and poor reliability limit the practical application of these fiber‐shaped supercapacitors. To overcome these problems, a new zinc‐ion hybrid fiber supercapacitor (ZHFSC) is designed and realized. As both capacitor‐type and battery‐type energy storage mechanisms can be used, the energy density of ZHFSC is expected to be improved. Furthermore, the excellent self‐healability of poly(vinyl alcohol) (PVA)/Zn(CF3SO3)2 aqueous gel electrolyte contributes to the high reliability of the ZHFSC. As a proof of concept, the maximum power density and energy density of the ZHFSC are, respectively, as high as 1433.2 mW cm−3 and 13.1 mWh cm−3, and the capacitance retention, respectively, has the high values of 87.8% and 70.5% under the bending degree of 150° and after the fifth self‐healing. This study offers an efficient method to realize the high‐performance supercapacitors for flexible wearable devices in the future. [ABSTRACT FROM AUTHOR]

Abstract: The design of transition‐metal chalcogenides (TMCs) photocatalysts for water splitting is highly important, in which both light absorption and interfacial engineering play vital roles in photoexcited electron generation, electron transport, and ultimately speeding up water splitting. To this end, plasmonic metal nanomaterials with surface plasmon resonances are promising candidates. However, it is very difficult to enhance the light absorption and manage the interfacial engineering simultaneously, thus, resulting in suboptimal photocatalytic performance. Here, a doped semiconductor plasmon is proposed to optically and electrically enhance TMCs hydrogen evolution. With the tunability of plasmon resonance in a doped MoO3 semiconductor via hydrogen reduction, the broadband absorption and good interfacial engineering are simultaneously demonstrated in flexible MoS2@MoO3 core–shell nanowire photocatalysts. Better energy‐band alignment with MoS2 can also be realized, thereby achieving improved photoinduced electron generation. More importantly, the defects at the interface between MoO3 and MoS2 are effectively reduced because of precise tunability of plasmon resonance, which enhances electron transport. As a proof of concept, this optimized hybrid nanostructure exhibits outstanding H2 evolution characteristics (841.4 μmol h−1 g−1), excellent stability, and good flexibility. The value is also one of the highest hydrogen evolution activity rates to date among the two dimensional‐layered visible‐light photocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: A modified detailed balance model is built to understand and quantify efficiency loss of perovskite solar cells. The modified model captures the light‐absorption‐dependent short‐circuit current, contact and transport‐layer‐modified carrier transport, as well as recombination and photon‐recycling‐influenced open‐circuit voltage. The theoretical and experimental results show that for experimentally optimized perovskite solar cells with the power conversion efficiency of 19%, optical loss of 25%, nonradiative recombination loss of 35%, and ohmic loss of 35% are the three dominant loss factors for approaching the 31% efficiency limit of perovskite solar cells. It is also found that the optical loss climbs up to 40% for a thin‐active‐layer design. Moreover, a misconfigured transport layer introduces above 15% of energy loss. Finally, the perovskite‐interface‐induced surface recombination, ohmic loss, and current leakage should be further reduced to upgrade device efficiency and eliminate hysteresis effect. This work contributes to fundamental understanding of device physics of perovskite solar cells. The developed model offers a systematic design and analysis tool to photovoltaic science and technology. [ABSTRACT FROM AUTHOR]

While indirectly patterned organic-inorganic hybrid perovskite nanostructures have been extensively studied for use in perovskite optoelectronic devices, it is still challenging to directly pattern perovskite thin films because perovskite is very sensitive to polar solvents and high-temperature environments. Here, a simple and low-cost approach is proposed to directly pattern perovskite solid-state films into periodic nanostructures. The approach is basically perovskite recrystallization through phase transformation with the presence of a periodic mold on an as-prepared solid-state perovskite film. Interestingly, this study simultaneously achieves not only periodically patterned perovskite nanostructures but also better crystallized perovskites and improved optical properties, as compared to its thin film counterpart. The improved optical properties can be attributed to the light extraction and increased spontaneous emission rate of perovskite gratings. By fabricating light-emitting diodes using the periodic perovskite nanostructure as the emission layers, approximately twofold higher radiance and lower threshold than the reference planar devices are achieved. This work opens up a new and simple way to fabricate highly crystalline and large-area perovskite periodic nanostructures for low-cost production of high-performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Currently, most of the promising organic solar cells (OSCs) are based on low bandgap polymer donors with deep-lying highest occupied molecular orbit (HOMO) levels, which impose the challenges for device architecture design. In terms of fast charge extraction and suppression of bimolecular recombination, elaborate interface design in low bandgap OSCs is of significance to further boost their ultimate efficiency. In this work, a facile solution-processed functionalized single wall carbon nanotube (f-SWCNT) mesh/self-assembled molecule (SAM) hybrid structure is reported as hole transport layer (HTL) in low bandgap OSCs. The effectiveness of such hybrid HTL originates from two aspects: (i) SAM layer can effectively realize Ohmic contact between f-SWCNT and low bandgap polymer donors with deep-lying HOMO levels due to the reduction of interface energy barrier; (ii) f-SWCNT mesh can provide fast hole extraction pathways to quickly sweep out photogenerated charges. As a consequence of synergic effects of such hybrid HTL, both photocurrent and fill factor are greatly enhanced due to the reduced bimolecular recombination. Together with careful light management by using ZnO optical spacer, a high efficiency of 10.5% has been achieved. This work offers an excellent choice for large-scale processable and effective HTL toward the application in low bandgap OSCs with deep-lying energy levels. [ABSTRACT FROM AUTHOR]

Broadband absorption enhancement in metal nanomaterials for high‐performance organic solar cells (OSCs) is highly desirable in the plasmonic‐enhanced OSCs. Here, a new dual plasmonic device is proposed by strategically designing device structures and managing two types of plasmonic structures (e.g., metal grating and metal nanoparticles (NPs)) in one device to achieve the broadband enhancement with better reproducibility, including (a) selecting Ag grating with 600 nm period as an anode, (b) introducing metal NPs into the electron transport layer (not active layer), and (c) adopting ZnO as the electron transport layer (not TiO2). The device shows broadband absorption enhancement in the range of 350–800 nm due to multiple plasmonic effects. As a result, the maximum power conversion efficiency (PCE) of 9.62% has been achieved from the device, which is one of the highest efficiencies in plasmonic OSCs reported for a single junction OSC. Importantly, the as‐proposed dual device in this work shows an excellent reproducibility of high PCE in experiment, which is much more applicable for practical applications. This work demonstrates the significance of rational design of the device structure and plasmonic nanostructures in achieving high‐performance plasmonic OSCs with broadband plasmonic absorption enhancement and reliable reproducibility. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) organic photodetectors (OPDs) operated in the photovoltaic mode, achieving a very high on/off ratio of 105 and a fast response time of 20 ns (a decay time of 888 ns), are demonstrated in this work. Light‐induced tuning of the barrier height at the two interfaces of the carrier‐extraction layer and light‐induced tuning of series resistance are proposed to obtain the high on/off ratio. Fast response of the device is demonstrated through the ultrafast trap filling process. The high on/off ratio and fast response are simultaneously realized by introducing TiO2 nanocrystals as the electron‐extraction layer of OPDs. In addition, the good on/off ratio can be maintained in a wide concentration range of 2,2′‐(1,3‐phenylene)bis[5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole] (OXD‐7) from 25% to 3.75% in the N,N′‐bis(naphthalen‐1‐yl)‐N,N′‐bis(phenyl)benzidine (NPB):OXD‐7 active layer and the corresponding OPDs can also achieve a fast response time simultaneously, good for its practical application. With the optimized device structure, a large detectivity of over 1012 Jones covering the UV‐A region (320–400 nm) and a high linear dynamic range of 100 dB are obtained. Additionally, stability of TiO2‐based OPDs, which is not well studied but an important parameter for OPDs, is experimentally investigated. [ABSTRACT FROM AUTHOR]

It is widely accepted that surface enhanced Raman scattering (SERS) enhancement results from a combination of electromagnetic mechanisms (EM) and chemical mechanisms (CM). Recently, the nanoparticle-film gap (NFG) system was studied due to its strong local enhancement field. However, there are still some technical limitations in establishing effective and simple ways for reliable and precise control of sub-nanospacer. In addition, works on designing the nanospacer in NFG system for efficient interaction with target molecules for further improving SERS signals are rather limited. Here, a novel NFG system is proposed by introducing ultrathin monolayer graphene as well-defined sub-nanospacer between Ag NPs and Ag film (named G(graphene)-NFG system). The new G-NFG system offers tremendous near-field enhancement with one of the highest enhancement ratio of 1700 reported to date. These results show that the single-layer graphene as a sub-nanospacer renders the proposed G-NFG system with particularly strong EM enhancement (due to multiple couplings including the NP-NP couplings and NP-film couplings) and additional CM enhancement in detecting some π-conjugated molecules to function as a powerful tool in analytical science and the related fields. [ABSTRACT FROM AUTHOR]

Lead halide perovskite solar cells (PSCs) have demonstrated power conversion efficiencies comparable to silicon‐based solar cells, yet their instability under environmental stressors, such as humidity, heat, and light, remains a significant barrier to commercialization. A primary cause of this instability is the uncoordinated lead ions (Pb2+), which accelerates the degradation of PSCs and pose environmental concerns due to potential lead leakage. Recently, the introduction of ligands into PSCs has shown promise in mitigating lead toxicity through effective passivation, primarily by forming hydrogen bonds (H‐bonds) between functional groups of the ligands and the perovskite structure. In this minireview, we explore the critical role of H‐bonds in stabilizing PSCs by enhancing the structural integrity of the perovskite layer and reducing lead leakage. Furthermore, we discuss the contribution of these ligands in defect passivation, hydrophobicity, self‐encapsulation, cross‐linking, and self‐healing mechanisms. These insights will highlight the multi‐functional capabilities of ligands in improving the long‐term stability and durability of PSCs, offering pathways to address current challenges in their commercialization. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PVSCs) have emerged as a promising candidate for addressing the energy crisis due to their rapid efficiency improvement up to 24.2% within 10 years. The defects existing in perovskite film have been found to be as low as 1015 cm−3 indicating that the bulk nonradiative recombination loss is very small. The major efficiency loss has been attributed to inefficient carrier transportation and collection, particularly at the interfaces of the carrier transport layers (CTLs). Moreover, the mobile ions that can penetrate into or be blocked by the CTLs have been considered to play a significant role in the determination of device efficiency and stability. The further improvement of the PVSC performances relies on interfacial engineering. Meanwhile, it is highly desirable to gain an in‐depth physical understanding of interfacial engineering in PVSCs. Herein, the recent works on CTLs in planar PVSCs are reviewed and the device physics for designing high‐performance PVSCs is unveiled. This work describes the (1) materials and strategies for efficient CTLs; (2) effects of mobile ions and the influence of CTLs; and (3) theoretical modeling and understanding of PVSCs. This work can, therefore, contribute to designing and improving high‐performance PVSCs for future practical commercialized applications. [ABSTRACT FROM AUTHOR]

While there are very limited studies of doped ternary metal oxide based hole transport materials, a multifunctional synthesis approach of In doped CuCrO2 nanoparticles (NPs) as efficient hole transport layers (HTLs) including simplifying the synthesis requirements is proposed, enabling doping and achievement of treatment‐free HTLs. Remarkably, compared with conventional methods for synthesizing CuCrO2 NPs, the newly proposed azeotropic promoted approach dramatically reduces the reaction time by 90% and the calcination temperature by one‐third, which not only promotes high throughput production but also reduces power consumption and cost in synthesis. Equally important, indium is successfully doped into CuCrO2, which is fundamentally difficult in low temperature processes. The In doping offers less d–d transition of Cr3+ and p‐type doping characteristics for improving HTL transmittance and conductivity, respectively. Interestingly, In doped CuCrO2 HTL with these improvements can be achieved by a simple ambient‐condition process and exhibits thermal stability up to 200 °C, which allows perovskite solar cells (PSCs) to achieve a power conversion efficiency of 20.54%. Meanwhile, the devices show good repeatability and photostability. Consequently, the work contributes to establishing a simple approach to realize pristine and doped multinary oxides based HTL for the development of practical and high performing PSCs. [ABSTRACT FROM AUTHOR]

Ultrathin monolayer graphene as a welldefined sub‐nanospacer between Ag NPs and Ag film is demonstrated by C. H. Choy and co‐workers. Their results show that the system offers a tremendous near‐field enhancement with one of the highest enhancement ratios reported to date in the graphene–metal plasmonic combination system. There is an additional chemical enhancement from the interaction between graphene sub‐nanospacer and detection molecules. [ABSTRACT FROM AUTHOR]