ABSTRACT A high‐quality quantum dots (QDs) layer is crucial for the commercialization of quantum dot light‐emitting diode (QLED) devices. However, current fabrication techniques cannot simultaneously achieve monolayer coverage, ordered arrangement, and large‐area scalability. Herein, we develop a novel strategy of continuous stepwise self‐assembly for QDs monolayer integrated the air‐liquid interfacial assembly technology with continuous line‐ink‐supply and Langmuir‐Schaefer (LS) technology, which the QDs can be finely to assemble into large area ordered and dense QDs monolayer film at the trailing edge of the flow. The ordered QD monolayers can be repeatedly transferred and stacked to accurately control the thickness of the luminescent layer in QLED devices. Green QLED based on this monolayer film reaches a high EQE of 23.85%. Furthermore, the optimized trilayer device exhibits negligible efficiency roll‐off, retaining an EQE above 18% and a luminous efficacy of 60 lm W −1 at a luminance of 200 000 cd m −2 . This methodology also shows preliminary scalability potential. We achieved a trial fabrication of large‐area QD films of 210 cm 2 and further constructed corresponding QLED devices with an emission area of 1.5 cm × 1.5 cm as an initial exploration.

Electrodeposited Cu2ZnSn(S,Se)4 (CZTSSe) on fluorine-doped tin oxide (FTO) is promising for transparent photovoltaic devices yet constrained by inhomogeneous nucleation, inferior crystallization, and severe back-contact barriers, limiting its efficiency to ∼4.7%. Herein, a Ag nanoseed layer is developed to synergistically regulate the electrodeposition kinetics and postselenization crystallization. The Ag nanoseeds afford abundant highly active heterogeneous nucleation sites to reduce Cu2+ migration barriers and yield dense uniform metallic precursors. Upon selenization, the generated low-melting Ag-Sn-Se liquid phase accelerates grain growth and suppresses deep-level defects. Meanwhile, Ag incorporation tailors interfacial energy-level alignment and converts the unfavorable Schottky hole barrier into a hole-transport-favorable interface. Owing to these combined effects, the optimized device achieves an impressively enhanced efficiency from 3.22% to 6.30%, setting a new efficiency record for FTO-based electrodeposited CZTSe devices. This work offers a facile route toward efficient, low-cost chalcogenide photovoltaics for transparent optoelectronics.

Selenium (Se), due to its inherent stability, low environmental toxicity, and adaptability to emerging applications such as indoor light harvesting and tandem solar cell architectures, has re-emerged as a promising material for next-generation photovoltaic power generation. However, the actual efficiency of selenium-based devices remains far lower than theoretical predictions, mainly due to the challenges in balancing the control of crystallinity and the mitigation of defects during the thin film manufacturing process. In this study, the role of the annealing time in optimizing the microstructure and electronic properties of selenium thin films was systematically investigated. By optimizing the annealing conditions to balance crystallization and material stability, we achieved an efficiency of 6.08 % while maintaining long-term operational durability. The contradiction between thin film microstructure and photovoltaic performance induced by annealing time essentially reflects a competition between thermodynamic driving forces and kinetic limitations over time. Advanced characterization techniques show that extended defects rather than point defects dominate the recombination losses, providing crucial insights into the efficiency limitations. This work establishes a scalable processing framework that links fundamental understanding with industrial compatibility, offers a pathway to unleash the full potential of selenium in photovoltaic power generation, and provides information for the thermal management strategies of related chalcogenides and materials with high saturated vapor pressure.

A key reason for Cu2ZnSn(S,Se)4 (CZTSSe, 15.8%) solar cells lagging far behind Cu(In,Ga)Se2 (CIGS, 23.6%) in efficiency is its inability to autonomously form a dual-gradient bandgap via Ga gradient, critical for the simultaneous efficient light absorption and directed carrier transport. Herein, this study proposes a novel strategy for the spontaneous construction of dual gradients CZTSSe with a S-rich front interface and a Ge-rich back interface based on SnS-GeSe co-sulfoselenization. SnS releases S vapor and Sn2Se3 intermediate phase during selenization, synchronously compensating for Sn volatilization loss and forming a S-rich surface layer, leading to a synergistic composition stability and interface defect passivation. Meanwhile, GeSe, by virtue of its eutectic property, promotes the migration and enrichment of Ge toward the back interface for an efficient back surface field and suppresses defects. The S-rich front widens the surface bandgap to improve open-circuit voltage (VOC), and the Ge-rich back elevates the back conduction band minimum (CBM) and suppresses the Sn-related defect to facilitate carrier transport. As a positive result, the optimized devices achieve a 26% enhancement in photovoltaic efficiency, offering a new insight for the development of high-efficiency kesterite-based solar cells.

Nanohybrids combining phenylboronic acid-modified carbon dots (PCDs) and proteinase K have been engineered for addressing the formidable challenges of antimicrobial photodynamic therapy (aPDT) against bacterial biofilm infections, overcoming biofilm barrier obstruction, the limited diffusion of reactive oxygen species (ROS), and the inadequate ROS generation of traditional photosensitizers. PCDs are formulated for superior water solubility and robust singlet oxygen (1O2) production, mitigating issues related to dispersion and aggregation-induced quenching typical of conventional photosensitizers. The conjugation of phenylboronic acid to CDs not only enhanced 1O2 generation through increased electron-hole separation but also imparted strong bacterial binding capabilities to the PCDs, enabling broad-spectrum sterilization by maximizing the ROS-mediated bacterial destruction. Proteinase K, serving as a structural "glue", actively breaks down biofilms and facilitates the deep penetration of functional PCDs, aiding effective treatment of biofilm infections. In vivo studies confirm that PCDs-proteinase K nanohybrids dramatically accelerate healing in biofilm-infected wounds by synergizing enhanced photosensitization, potent bacterial adherence, and efficient biofilm elimination and penetration. This approach highlights a straightforward strategy to significantly advance aPDT, promoting the clinical adoption of non-antibiotic methods for combating bacterial biofilm infections. STATEMENT OF SIGNIFICANCE: 1) Phenylboronic acid-modified carbon dots (PCDs) were designed for enhanced water solubility and efficient singlet oxygen generation through surface modulation, also suggesting that surface modification can improve the inherent photosensitizing activity of CDs by promoting electron-hole separation; 2) The conjugation of phenylboronic acid endowed PCDs with strong bacterial binding capabilities, enabling highly efficient and broad-spectrum sterilization by maximizing reactive oxygen species-mediated bacterial destruction; 3) Incorporation of proteinase K (PK) leveraged its specific extracellular polymeric substance degrading capability, along with the stimuli-responsive release of PCDs from the PCDs-PK nanohybrids, facilitating biofilm breakdown and enabling deeper penetration of PCDs, thereby improving the treatment of biofilm infections.

The Zinc-Magnesium oxide (ZnMgO, ZMO) nanoparticles (NPs) are well-documented as electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs). However, ZnO/ZMO nanoparticles prepared via low-temperature sol-gel methods with small grain size and abundant surface defects always suffer from structural and electrical drift, causing lifespan reduction and performance fluctuations of devices. Herein, the benzyl phosphate (BPA) and its derivatives are introduced onto the surface of ZMO NPs as armor layer to stabilize and regulate their properties as ETLs. The prepared ZMO capped with BPA NPs have fine structural and electrical properties stability, which have simultaneously achieves effective defect passivation, enhances nanoparticle dispersibility and stability, and precisely tunes energy levels to balance charge injection. By benefiting from the robust ZMO ETLs, the overall performance of the QLED devices has been greatly boosted. The resulting external quantum efficiency (EQE) of green QLEDs is increased from 20.8% to 29.9%, showing the best performance among currently reported ZMO-based green QLEDs, and over 3.3-fold improvement in T95 operation lifetime at 1000 cd m- 2. The relevant physical mechanism has also been investigated. Current work will inspire the exploration of ZMO decorating engineering to construct solution-processed QLEDs device with higher performance.

Pathogenic bacterial spores pose a considerable threat to human health due to their ability to survive extreme environmental conditions. Thus, sensitive detection and efficient inactivation of these spores are essential for preventing disease transmission. However, most existing studies have predominantly concentrated on detection alone. Herein, we developed a versatile nanoplatform that integrates sensitive bacterial spore sensing and in situ spore inactivation capabilities by assembling terbium ions (Tb3+) with photosensitizing carbon dots (CDs), referred to as Tb-CDs nanoassemblies (NAs). By leveraging the unique optical properties of CDs and Tb3+ ions, along with the antenna effect of lanthanides, Tb-CDs NAs demonstrated highly sensitive visual detection of the key bacterial spore biomarker, pyridinedicarboxylic acid (DPA), achieving a low detection limit of 0.68 mu M and excellent selectivity. Additionally, Tb-CDs NAs exhibited practical sensing capabilities in various environments, including spore suspensions and real samples, while monitoring bacterial spore germination. Further studies confirmed that the DPA-triggered disassembly of Tb-CDs NAs led to the release of CDs, enabling higher affinity for spores and in situ inactivation through singlet oxygen generation. This work underscores the potential of CDs- based assemblies for simultaneous pathogen detection and inactivation, providing promising tools for preventing bacterial spread and contamination.

The poor efficiency and stability of blue quantum dot light-emitting diodes (QLED) hinder its practical applications in full-color displays. Insufficient hole injection and excessive surface defects in quantum dots (QD) layer remain the primary challenges limiting the performance of blue devices. Herein, a dual interface modification strategy is proposed to enhance the performance of blue QLED by synergistically regulating both the electronic transport layer (ETL)/QD and hole transport layer (HTL) HTL/QD interfaces. At the HTL/QD interface, the introduction of guanidine sulfamate (GAS) ligands passivates QD surface defects while reducing the hole injection barrier, thereby improving hole injection efficiency in the low-bias region. Meanwhile, at the QD/ETL interface, Guanidine chloride (GACl) ligands are incorporated to passivate interfacial defects, suppress leakage current, and suppress excessive electron injection, thus enhancing hole transport efficiency within the QDs layer. The synergistic effect of bilateral GA-based ligands can simultaneously enhance the hole injection efficiency based upon improving the hole transport efficiency, significantly increasing the radiative recombination ratio during device operation. As a result, the dual-ligand modified blue QLEDs achieve a remarkable improvement in external quantum efficiency (EQE) from 16.6% to 24.3%, and a sevenfold enhancement in operational lifetime.

Flexible Cu2ZnSnSe4 (CZTSe) solar cells hold great potential for low-cost green fabrication and portable applications, yet electrodeposited devices suffer from low efficiency (∼6% vs 12.84% for solution-processed ones), primarily due to defect-induced nonradiative recombination and carrier loss at back interfaces. Herein, a dual-functional GeSe-Se coselenization strategy is proposed to simultaneously achieve defect regulation and back-interface engineering. Ge substitution for Sn during selenization induces lattice contraction, effectively suppressing Sn-related deep defects and band-tail states while minimizing the secondary phase. Simultaneously, Ge diffuses into the MoSe2 interface layer to optimize the energy-level alignment and reduce nonradiative recombination. Consequently, the optimized flexible CZTSe solar cells achieve a record efficiency of 9.01%, the highest among electrodeposited flexible CZTSe devices. This study elucidates the synergistic role of Ge in simultaneously mitigating bulk defects and refining interfacial energetics, highlighting a remarkable achievement for electrodeposition-based flexible CZTSe solar cells.

Pure sulfide-based Cu2ZnSnS4(CZTS) stands as a competitive photovoltaic material, composted of earth-abundant, low-cost, and stable constituent elements. The stacked electrodeposition process has garnered attention owing to its facile regulation of elemental composition, and its non-vacuum, room-temperature, water-based solvent operating conditions. However, the limitation based on the stacked electrodeposition-processed CZTS primarily stems from the numerous defects and detrimental interfaces induced by the deficient intermetallic diffusion. Herein, a Se nanoparticle layer at the back interface is introduced to enhance the intermetallic diffusion, optimize the precursor morphology, and subsequently accelerate the grain growth. Comprehensive characterizations reveal Se, acting as the hetero-nucleation seeds, catalyzes Cu deposition and promotes a highly porous structure with a homogeneous elemental distribution. Consequently, high-quality CZTS with enhanced crystallinity and passivated defects is achieved, thereby promoting carrier transport and suppressing non-radiative recombination. These sequential positive effects result in a substantial improvement in short current density (Jsc) and fill factor (FF), attaining an improved efficiency. Our findings offer a promising strategy to overcome the issues of the stacked electrodeposition-processed films and highly contribute to the development of high-quality CZTS-based solar cells.

Sb 2 Se 3 solar cells deposited by rapid thermal evaporation (RTE) have drawn extensive attention owing to their compatibility with the commercial production line of CdTe solar cells and can be used to fabricate high‐quality Sb 2 Se 3 films with high reproducibility. However, the deposition pressure during the RTE process has not been clearly explored, although it has a significant effect on the Sb 2 Se 3 film quality. A novel two‐step deposition strategy is proposed that finely regulates the deposition pressure to improve the quality of Sb 2 Se 3 absorber layers, thereby improving the device performance of Sb 2 Se 3 solar cells. This novel method includes a rapid deposition process under a low pressure (5 mTorr) and an in situ annealing process under a relatively high pressure (200 Torr). The maximum power conversion efficiency (PCE) of Sb 2 Se 3 solar cells fabricated by two‐step deposited approach is up to 8.12%. The PCE enhancement is attributed to the increased grain size, reduced grain boundaries, modified surface Fermi level gradient of the absorber layer, and improved defect performance. This innovative deposition technique is expected to benefit other low‐melting‐point metal sulfoselenides for solar cell applications.

Sn-free Cu2ZnGeSe4 (CZGSe) is emerging as a promising non-toxic and earth-abundant photovoltaic absorber material due to its attractive electrical and optical properties as well as its high theoretical conversion efficiency. Nevertheless, no photovoltaic device fabricated through the green electrodeposition process has yet been reported, likely due to the poor solubility of Ge-based salts and harsh electrodeposition conditions. Herein, we propose a GeSe-evoked synchronous strategy involving a Ge incorporation and selenization-regulated co-heating process of GeSe and Se, following electrodeposition of a Cu-Zn preformed layer. We experimentally found that the low-melting-point GeSe could promote the crystal growth and induce a high-quality bulk absorber layer and good back interface. In the GeSe-promoted sample, it was found that MoSe2 could ensure a good back quasi-Ohmic contact, and the band bending at the grain boundaries (GBs) was favorably inverted. Moreover, the depletion region width was also prolonged, and the deleterious CuZn near EF was passivated, leading to an increased carrier separation. In turn, a surprising progress in device performance was found, achieving a ground-breaking efficiency of 3.69%, and it could fill the bank of green electrodeposited CZGSe-based solar cells.

Bifacial flexible solar cells are considerably attractive owing to their high generation of energy per area and multidirectional light irradiation in advanced applications, such as building-integrated photovoltaics. Their technological ability to reduce manufacturing costs and time is highly essential. Although the solution-processed technique has implemented bifacial flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, no progress on the green electrodeposition process has occurred. Herein, we first propose symmetrical bifacial Cu2ZnSnSe4 (CZTSe) solar cells through a facile electrodeposition process, in which Mo foils are used as a common back electrode for both sides. Stacked electrodeposition accomplished at one time is involved to produce high-quality bifacial CZTSe absorber layers. This strategy can guarantee the consistency of bifacial flexible solar cells and immensely low costs and time. The resultant high efficiencies of 6.43% and 6.20% for the two sides have made a great breakthrough for electrodeposited flexible CZTSSe devices and offered a cost-effective strategy for green-processed material fabrications. Compared with the solution-processed technique, the determined interfacial-suppressed Voc limiting the efficiency provides a clear aspect for further improving the efficiency. A symmetrical bifacial flexible Cu2ZnSnSe4 (CZTSe) solar cells are fabricated through a green electrodeposition process with championed efficiencies for both sides.

Antimony selenide (Sb2Se3) has been applied extensively in the field of optoelectronics because of its excellent material and photoelectric properties, as well as its potential low cost effectiveness. Owing to its unique quasi-one-dimensional structure, the preparation of an Sb2Se3 absorption layer with high crystallization quality and standing preferred orientation is crucial for constructing high-performance Sb2Se3 devices. Herein, we reported a new method for the subsequent epitaxial growths of Sb2Se3 thin films with high crystallization and preferred standing orientations using the Sb2Se3 nanorod array as growth template on the Mo substrate and summarized the growth mechanism of the nanorod arrays. High crystal quality and crystal orientation can be easily controlled, carrier recombination is reduced, charge transport is enhanced, and the performance of Sb2Se3 device is improved significantly. As high as 6.3 % power-to-efficiency with a fill factor of 62 % has been achieved for the champion device. This general-purpose nanorod array template growth film provides an effective reference for the growth control of other low latitude crystal films.

Due to the difficulty in controlling the post-selenization/sulfurization process accurately, single-graded structure with a lower bandgap on the surface is easy to form in the Cu2ZnSn(S, Se)4 absorber. This will lower the built-in potential and lead to the formation of undesirable “cliff” type band alignment in the device, and hence a drastic Voc-deficit and lower efficiency are expected. Herein, an effective and versatile method to improve the Voc and efficiency of Cu2ZnSn(S, Se)4 solar cells through bandgap engineering was presented in this work. A sharp surface bandgap gradient with larger surface bandgap was constructed simply by sputtering a nanoscale Cu2ZnSnS4 layer on the surface of Cu2ZnSn(S, Se)4 absorber. Under the coactions of surface sharp bandgap gradient and the single bandgap gradient existed in the Cu2ZnSn(S, Se)4 absorber naturally, a quasi-U-shaped bandgap gradient was constructed inside the absorber. Benefited from the enlarged surface bandgap, favorable U-shaped bandgap gradient and appropriate band alignment at the absorber/buffer interface, a best efficiency of 9.9% with a Voc of 450 mV, a Jsc of 35.26 mA/cm2 and a fill factor (FF) of 62.73% was achieved.

Selenization is effective to fabricate high-efficiency kesterite Cu2ZnSnSe4 (CZTSe) solar cells that facilitates the composition modification, crystallization enhancement, and bandgap adjustment. The incorporation of Sb into CZTSe absorbers can further boost the device efficiency mainly due to promoting the grain growth of CZTSe absorber. Here we report a Sb2Se3 and Se co-selenization process that significantly improves the quality of CZTSe absorber layers. This strategy enables the increase of CZTSe grain size and elimination of pinholes. We find that Sb is uniformly distributed in the absorber layer. When the Sb/(Cu + Zn + Sn) ratio is tuned to 6.67 parts per thousand, the CZTSe solar cell exhibits the best device performance with an efficiency up to 9.64%, over 40% higher than the traditional selenization process. Our work provides a new route for enhancing the device efficiency of CZTSe solar cells.

Given the prominent success of the Ga gradient in CuIn1-xGaxSe2 (CIGSe) solar cells, Ge gradient implementation is a promising way to boost Cu2ZnSn(S,Se)(4) (CZTSSe) solar cells. However, Ge-graded CZTSSe solar cells only possess a low efficiency of 9.2%, far from that of Ge-incorporated CZTSSe without a gradient (12.3%). Herein, we demonstrated a shallow Ge gradient CZTSe solar cell with an improved efficiency over 10%. The Ge gradient was achieved through a GeSe2-Se coselenization process, where GeSe2 acts as a low-temperature fluxing agent to assist crystallization and induce Ge transport toward the back interface. The relieved band tails and improved junction quality, leading to a better carrier separation, were found to take a primary responsibility for device improvement. These results highlight a remarkable breakthrough for Ge-graded CZTSe solar cells and offer a promising way to develop Ge-involved solar cells.

An integration strategy of chemical welding and subsequent protection was demonstrated to address silver nanowires (Ag NWs)-based issues. Preferentially, a halogenated salt of NaCl solution was used to stimulate the junction welding thus to reduce the junction resistance, by virtue of the autocatalytic redox of Ag atoms with halogen ions and dissolved oxygen molecules. Subsequently, chitosan, possessing the biocompatible, degradable, environmentally friendly non-toxic features, was embedded to protect Ag NWs. With these two steps, the composite electrode consisting Ag NWs and chitosan reaches a lowest sheet resistance of ∼8 Ω, with a transmittance over 80% at 550 nm, along with high thermal and chemical stabilities, accompanying with excellent flexibility. Besides, it also prompts a synergistic improvement when pioneered in Cu(In, Ga)Se2(CIGS) device as a transparent conductive electrode. It yields a power conversion efficiency of 6.6%, with 32% improvement relative to that bare Ag NWs, and 85% of the conventional one. Our findings present a new strategy for addressing instable/inefficient Ag NWs-based devices, driving their rapid development and its practical applications.

Flexible Cu2ZnSnSe4 (CZTSe) solar cells gradually attract much attention due to their low-cost, lightweight, and environmentally friendly features. However, the efficiency of flexible CZTSe solar cells obtained through the nonvacuum green electrodeposition process remains sluggish (3.82%), far away from that obtained from other methods (∼10% by magnetron sputtering). Herein, a championed 6.33% efficiency of flexible CZTSe solar cells prepared by the electrodeposition process is achieved through an in situ electrochemical treatment (ET) process. It is found that the ET process drives the formation of a thin MoOx layer, evoking a series of beneficial results, thus accounting for an enhancement in photovoltaic performance. With the ET process, the MoSe2 thickness is compressed and Cu- and Sn-related undesirable defects/secondary phases are inhibited, leading to improved film quality. Additionally, it prolongs the depletion region width and minority lifetime, accelerates the charge separation and collection, relieves the band tails, and favorably reverses the band bending from downward to upward at/near grain boundaries. With these effects, the efficiency increases from 4.21% to 6.33%, far beyond the highest reports on electrodeposited flexible CZTSe solar cells. Our findings offer a promising way to improving Mo foil-based flexible devices and mark a significant breakthrough for the development of electrodeposition-processed flexible CZTSSe-based solar cells.

A sequential route for low-cost fabrication of high quality Ag-alloyed CIGS absorbers is reported. Ag-alloying is introduced into the CuInGa precursor to widen the band gap and improve the crystallinity of the ACIGS absorbers. The morphological, compositional, and structural characteristics of the ACIGS absorber are also systematically investigated. Different Ag thin layer incorporation locations at the bottom, in the middle and on the top of CuInGa precursors are schemed for deep understanding the band gap energy and crystallinity regulation mechanism of Ag alloying. A conversion efficiency of 10.2% is achieved for the ACIGS device with Ag at the bottom. The notable Voc improvement can be obtained due to the widened band gap and the band gap gradient in the absorber created by the Ag and Ga elements grading. Finally, the ACIGS absorbers are further sulfurized and a highest power conversion efficiency of 13.01% is obtained. Our results indicate that the sequential magnetron sputtering is a promising way for the fabrication of CIGS thin film solar cells.