Efficient Charge Transport Research Articles

Fibrous Pb(II)‐Based Coordination Polymer Operable as a Photocatalyst and Electrocatalyst for High‐Rate, Selective CO2‐to‐Formate Conversion

AbstractA nonporous [Pb(tadt)]n (tadt = 1,3,4‐thiadiazole‐2,5‐dithiolate) coordination polymer, KGF‐9, with a 2D infinite (−Pb−S−)n structure has been previously reported as a precious‐metal‐free photocatalyst for selective CO2‐to‐formate conversion under visible light. In the present work, a microwave (MW)‐assisted solvothermal reaction is used to synthesize KGF‐9 with improved physicochemical properties and catalytic activity. Compared with KGF‐9 prepared by the previously reported methods, that prepared by the new synthesis route exhibited a greater specific surface area, greater crystallinity, and greater photoconductivity. These improved properties led to a drastic increase of the apparent quantum yield (AQY) for selective formate production, from 2.6 to 25% at 400 nm; this AQY represents a record‐high value among reported heterogeneous photocatalysts for CO2‐to‐formate conversion. Interestingly, the AQY for formate production is unchanged irrespective of the light intensity (0.04–14 mW cm−2), indicating little contribution of charge accumulation in the bulk during the reaction (i.e., indicating efficient charge transport to surface reactants). When composited with Ketjen Black, KGF‐9 enabled the electrochemical conversion of CO2 to formate in aqueous solution while maintaining a high selectivity. A high‐rate reduction of CO2 to formate with a total absolute current density of 200–300 mA cm−2 is achieved, with a Faradaic efficiency (FE) of >90%.

TVT‐Based New Building Block with Enhanced π‐Electron Delocalization for Efficient Non‐Fused Photovoltaic Acceptor

AbstractTo address the high‐cost issue that impedes the large‐scale fabrication and industrialization of organic solar cells (OSCs), it is crucial to design low‐cost photovoltaic materials with simplified synthesis procedures. In this study, a novel fully non‐fused acceptor, ATVT‐BO, featuring a triisopropylbenzene‐substituted (E)‐1,2‐di(thiophen‐2‐yl)ethene (TVT) unit as the central core is designed and synthesized. A control acceptor, A4T‐BO, with the same alkyl chains but a bithiophene central core, is also synthesized for comparison. Theoretical calculations and practical measurements reveal that compared to A4T‐BO, the insertion of an ethylene bond in ATVT‐BO enhances the molecular planarity and reduces the aromaticity, leading to enhanced π‐electron delocalization and thus improved electron mobility and a red‐shifted optical absorption spectrum. The 3D molecular packing mode of ATVT‐BO, characterized by tight intermolecular interactions, also promotes efficient charge transport in OSCs. Consequently, when paired with the low‐cost polymer PTVT‐T, featuring an ester‐substituted TVT structure, as the photoactive layer, the PTVT‐T:ATVT‐BO‐based device achieves a remarkable power conversion efficiency of 14.8%, distinctly higher than that of PTVT‐T:A4T‐BO‐based cell. The result highlights the significant potential of TVT units in creating both low‐cost polymer donors and fully non‐fused acceptors, which opens up new possibilities for designing low‐cost photoactive materials in OSCs.

Ethanol Processable Inorganic‐Organic Hybrid Hole Transporting Layers Enabled 20.12 % Efficiency Organic Solar Cells

AbstractIn this study, a high‐performance inorganic‐organic hybrid hole transporting layer (HTL) was developed using ethanol‐soluble alkoxide precursors and a self‐assembled monolayer (SAM). Three metal oxides‐vanadium oxide (VOx), niobium oxide (Nb2O5), and tantalum oxide (Ta2O5)‐were synthesized through successive low‐temperature (100 °C) thermal annealing (TA) and UV‐ozone (UVO) treatments of their respective precursors: vanadium oxytriethoxide (EtO−V), niobium ethoxide (EtO−Nb), and tantalum ethoxide (EtO−Ta). Among these, the Nb2O5 film exhibited excellent transmittance, a high work function, and good conductivity, along with a more compact and uniform structure featuring fewer interfacial defects, which facilitated efficient charge extraction and transport. Furthermore, the deposition of a SAM of (2‐(9H‐carbazol‐9‐yl)ethyl)phosphonic acid (2PACz) on top of Nb2O5 further passivated defects, enhancing interfacial contact with the photoactive layer. The resulting inorganic‐organic hybrid HTL of Nb2O5/2PACz demonstrated excellent compatibility with various photoactive blends, achieving impressive power conversion efficiencies of 19.44 %, 19.18 %, and 20.12 % for the PM6:L8‐BO, PM6:BTP‐eC9, and D18:BTP‐eC9 based organic solar cells, respectively. 20.12 % is the best performance for bulk heterojunction organic solar cells with binary components as the photoactive layer.

Structurally ordered FeCo@FeCoOx@NC dual-shell nanoparticles synthesized under micro-oxygen conditions: An efficient cocatalyst for BiVO4 photoelectrochemical water oxidation

Electrocatalysts are usually integrated onto light-absorbing semiconductors to form efficient photoelectrochemical water-splitting systems. Transition metal oxide nanoparticles serve as excellent electrocatalysts, but exhibit poor performance as cocatalysts for photoelectrodes. To address this issue, a FeCo@FeCoOx@NC dual-shell nanoparticle (consisting of a FeCo alloy core, an intermediate FeCoOx shell, and an outermost graphitic carbon shell) was prepared under micro-oxygen conditions. The FeCo alloy has the dual functions of rapid hole storage and efficient charge transport, while the FeCoOx layer acts as active sites to accelerate the kinetics of the water oxidation reaction and the graphitic carbon protects the internal structure of the nanoparticles. Under the synergistic effect of FeCo@FeCoOx@NC and NiFeOx cocatalysts, the injection efficiency and separation efficiency of BiVO4 photoanode almost reach 100 %, and the photocurrent density reaches 6.85 mA cm−2 (1.23 VRHE, AM 1.5 G), marking the highest reported value to date.

Multiscale Analyses of Strain-Enhanced Charge Transport in Conjugated Polymers.

The advancement of flexible and wearable electronics relies on semiconducting polymers that can endure mechanical deformation while maintaining high electrical performance under strain. In this study, we demonstrate that fine-tuning backbone rigidity through the molecular design of donor moieties significantly enhances both the mechanical and charge transport properties of diketopyrrolopyrrole (DPP)-based polymers. Specifically, the flexible DPP-4T (quaterthiophene) exhibited a persistence length of 20.4 nm in solution, while DPP-DTT (dithienothiophene) showed a longer persistence length of 32.8 nm due to its stiff backbone, as confirmed by small-angle neutron scattering and Monte Carlo simulations. This flexibility enabled DPP-4T to achieve a crack-onset strain exceeding 100% via the film-on-elastomer method and a fracture strain of over 30% in quasi-free-standing films. Additionally, DPP-4T demonstrated a 180% increase in hole mobility at 80% strain, driven by strain-induced chain alignment and backbone planarization. Utilizing a range of characterization techniques, including ultraviolet-visible (UV-vis) spectroscopy, grazing incidence X-ray diffraction (XRD), and Raman spectroscopy, we characterized structural changes at multiple length scales under applied tensile strain. Notably, strain induced a transformation in chain conformation from a twisted to a flat structure, reducing the hopping energy barrier and enhancing charge transport. These structural rearrangements are crucial for sustaining efficient charge transport and ensuring the reliability of electronic performance under mechanical stress.

Z-scheme heterojunction photocatalyst of LaFeO3@CoS for tetracycline hydrochloride degradation by persulfate activation using visible light

An efficient and stable LaFeO3@CoS Z-scheme heterojunction photocatalyst was prepared through the hydrothermal method (HT). Photocatalytic activity of the LaFeO3@CoS was assessed by activating persulfate under visible light for the degradation of tetracycline (0.1 g/L). Under the condition of 0.06 g/L of KHSO5 (Peroxymonosulfate, PMS), the degradation efficiency of 88.7 % was achieved in 40 min using the 0.02 g/L of developed photocatalyst. The degradation kinetic constants of LaFeO3@CoS were 2.79 and 2.23 times higher than those of LaFeO3 and CoS, respectively. Furthermore, the catalyst exhibited excellent stability over five consecutive degradation cycles. Possible degradation mechanisms and the electron transfer mechanism of the heterojunction formed by the LaFeO3@CoS were investigated by quenching experiments, nitrogen N₂ purging experiments, electron spin resonance (ESR) measurements and corresponding electrochemical analyses. In the LaFeO3@CoS/Vis/PMS system, the Z-scheme charge transfer pathway not only accelerated charge transport efficiency but also effectively spatially separated electrons and holes, enhancing the photocatalytic performance of the photocatalyst. Additionally, the generation of reactive species such as 1O2, O2•−, and SO4• − significantly contributed to the improved degradation efficiency of the present catalyst during the degradation process.

Modulation of the Microstructure and Enhancement of the Photocatalytic Performance of g-C3N4 by Thermal Exfoliation

This work explores the impact of reaction temperature during thermal exfoliation treatment of bulk-g-C3N4 in the air atmosphere on the structure and performance of the resulting CN photocatalyst. The analysis conducted using XRD, FT-IR, XPS, SEM, and elements mapping tests, illustrated an increase in nitrogen-vacancy and oxygen content on the surface of the CN photocatalyst, resulting in a porous and sparse structure, changes in crystal size, and improved visible light absorption performance. The photocatalytic reduction experiments of hexavalent chromium (Cr(VI)) showed that the CN-540 showed the highest reduction rate of 96.9%, with a reaction rate constant 6.21 times that of bulk-g-C3N4. After 100 min of illumination, the photocatalytic degradation rates of CN-540 for TC-HCl and RhB were 66.7% and 60.6%, respectively. The TOC test results indicated mineralization rates of 51.5% for TC-HCl and 46.6% for RhB. Room temperature fluorescence spectroscopy (PL), transient photocurrent response (TPC), and electrochemical impedance spectroscopy (EIS) measurements confirmed the excellent photogenerated charge carrier separation and transport efficiency of CN-540. The photocatalytic mechanism for reducing Cr(VI) by CN-540 was elucidated based on the active species •OH and •O2– and Mott-Schottky (M-S) tests. This study provides experimental data for optimizing the photocatalytic performance of g-C3N4 and paves a new way for developing efficient photocatalysts. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Binder-free tin (IV) oxide coated vertically aligned carbon nanotubes as anode for lithium-ion batteries

Despite the tremendous potential of tin oxide (SnO2) as an anode material, irreversible capacity loss due to the sluggish kinetics and structural pulverization as a result of the substantial volume alteration during redox reactions limits its use in lithium-ion batteries. The typical layered design of an electrode consisting of binder and conductive additive can lower the practical capacity of high-capacity electrode materials. We synthesized a binder and conductive additive-free, self-standing core-shell vertically-aligned carbon nanotubes (VACNTs)-SnO2 anode (SnO2-VACNTs) on 3D nickel foam using plasma-enhanced chemical vapor deposition and wet chemical method. The SnO2-VACNTs exhibited excellent cyclability with a specific capacity of 1512 mAh g−1 at 0.1 A g−1 after 100 cycles and 800 mAh g−1 at 1 A g−1 after 200 cycles. The ultra-fine SnO2 particles (<5 nm) shortened the Li+ diffusion paths into the bulk electrode and alleviated the volume alteration by lowering the strains during the redox reactions. Also, proper inter-tube distance between individual SnO2-VACNTs buffered the volume instability and offered better electrolyte accessibility. Direct connection of VACNTs with the current collector ensured an uninterrupted electron conducting path between the current collector and active material, thus offering more efficient charge transportation kinetics at the electrode/electrolyte interfaces.

Bulk Heterojunction Perovskite Solar Cells Incorporated with Conjugated Polyfluorenes

Ambipolar transport characteristics of metal halide perovskites (MHPs) enable both hole and electron to be transported simultaneously in perovskite solar cells (PSCs); however, unbalanced charge transport is a fundamental limitation in boosting power conversion efficiency (PCE) of PSCs. Compared to the PSCs with either n–i–p or p–i–n device structures, bulk heterojunction (BHJ) PSCs, inspired by organic photovoltaics, are recognized as superior for balancing charge transport and maximizing interface interactions. This study reports high‐performance BHJ PSCs, where the BHJ composites are composted with the n‐type MHPs mixed with the p‐type conjugated polyfluorenes. In the systematic studies, it is indicated that a small amount of conjugated polyfluorenes component can boost the crystallinity and grain size of the MHP thin film. Moreover, BHJ composite thin films possess boosted charge carrier mobility and a tendency of balanced charge transport and suppress both radiative and non‐radiative charge carrier recombinations. Most importantly, an efficient photoinduced charge transport within the BHJ composite thin film boosts photocurrent. As a result, the PSCs based on the n‐type MHPs:p‐type conjugated polyfluorenes BHJ composite thin film exhibit 23.46% of PCE and boost stability. The results demonstrate a facial method to approach high‐performance PSCs.

MoS2/porous carbon nanofiber heterostructures for efficient evaporation-driven generators.

Evaporation power generators (EPGs) based on natural water evaporation can directly convert heat energy from the surrounding environment into electrical energy. However, EPGs are difficult to commercialize due to the low charge generation and transport efficiency of single material systems, resulting in unsatisfactory open-circuit voltages and short-circuit currents. Here, we step by step prepared MoS2/porous carbon nanofiber (PCNF) heterogeneous systems by electrospinning and hydrothermal methods. Electron microscope measurements proven the uniform coating of high-crystalline quality MoS2 nanosheets on PCNF fabrics, and the uneven concave-convex surface increased the specific surface area. MoS2 covered PCNF fabrics retained good hydrophilicity, which was suitable for absorbing water and keeping the surface wet during long-term evaporation. Moreover, layered MoS2 with rich surface charge improved the charge transfer of the MoS2/PCNF fabrics. As a result, the open-circuit voltage and short-circuit current of the EPGs prepared with MoS2/PCNF fabrics were improved to 0.25 V and 75 μA, respectively, compared with those based on PCNF fabrics, which demonstrated that the MoS2 coatings improved the interaction area with water and the charge transfer effect of the EPGs. This heterogeneous combination strategy provides ideas for the preparation of high-performance EPG materials.&#xD.

Synergistic Design of Imidazole-Based Polymer Donors for Enhanced Organic Solar Cell Efficiency.

Within the realm of organic solar cells (OSCs), designing new high-efficiency polymer donors remains a significant challenge. Achieving the right balance in polymer backbone planarity is crucial: excessive planarity can lead to undesirable aggregation, while insufficient planarity can hinder the charge transport efficiency. In this study, we designed and synthesized an imidazole-based acceptor (A) unit for the first time and then investigated the impact of backbone planarity on charge transport capacity and power conversion efficiency (PCE). Backbone planarity was precisely tuned by incorporating isomeric alkyl chains on the thiophene π-bridge, resulting in four distinct polymer donors: MZC8-F, MZC8-Cl, MZEH-F, and MZEH-Cl. The results showed that the steric hindrance from the EH-branched alkyl chain induced backbone distortion and caused a blue-shift in the absorption spectrum. MZEH-Cl, with its poor planarity and excessively low HOMO energy level, achieved a PCE of just 7.6%. Through careful modulation, MZC8-Cl emerged as the most efficient, with a remarkable PCE of 17.3%, setting a new benchmark for imidazole-based polymer donors. This study not only deepens the understanding of the role of polymer backbone planarity in photovoltaic performance but also lays the groundwork for developing high-efficiency polymer donors.

High‐Efficiency Deep‐Blue Solution‐Processed Organic Light‐Emitting Diodes Using Carbazole Dendrons Modified Hybridized Local and Charge‐Transfer Emitters

In the pursuit of efficient and cost‐effective organic light‐emitting diodes (OLEDs), the development of solution‐processed hybridized local and charge transfer (HLCT) emitters presents a promising approach. HLCT materials uniquely integrate the advantages of both singlet and triplet excitons, surpassing the traditional spin statistical limit of 25% while offering high photoluminescence efficiency and balanced charge transport properties. Herein, we report the synthesis and characterization of two new deep blue, solution‐processable HLCT fluorophores, G1FTPI and G2FTPI. These compounds incorporate fluorenyl carbazole dendron units into the HLCT luminogenic triphenylamine‐phenanthroimidazole (TPI) molecule. Their HLCT and photoluminescence (PL) properties were experimentally and theoretically investigated using solvation effects and density functional theory (DFT) calculations. The molecules exhibit deep blue emission with a high solid‐state fluorescence quantum yield, good solution‐processed film‐forming quality, and high hole mobility values of 2.18 – 2.61 × 10‐6 cm2 V‐1s‐1. Both compounds were successfully employed as non‐doped emissive layers in solution‐processed OLEDs, demonstrating excellent electroluminescent (EL) performance. Notably, the G2FTPI‐based device emitted a deep blue light at 432 nm with CIE coordinates of (0.158, 0.098) and achieved a a maximum current efficiency (CEmax) of 3.13 cd A‐1 and a maximum external quantum efficiency (EQEmax) of 5.30%.

Unraveling the Electrochemical Insights of Cobalt Oxide/Conducting Polymer Hybrid Materials for Supercapacitor, Battery, and Supercapattery Applications.

This review article focuses on the potential of cobalt oxide composites with conducting polymers, particularly polypyrrole (PPy) and polyaniline (PANI), as advanced electrode materials for supercapacitors, batteries, and supercapatteries. Cobalt oxide, known for its high theoretical capacitance, is limited by poor conductivity and structural degradation during cycling. However, the integration of PPy and PANI has been proven to enhance the electrochemical performance through improved conductivity, increased pseudocapacitive effects, and enhanced structural integrity. This synergistic combination facilitates efficient charge transport and ion diffusion, resulting in improved cycling stability and energy storage capacity. Despite significant progress in synthesis techniques and composite design, challenges such as maintaining structural stability during prolonged cycling and scalability for mass production remain. This review highlights the synthesis methods, latest advancements, and electrochemical performance in cobalt oxide/PPy and cobalt oxide/PANI composites, emphasizing their potential to contribute to the development of next-generation energy storage devices. Further exploration into their application, especially in battery systems, is necessary to fully harness their capabilities and meet the increasing demands of energy storage technologies.

Cation-Dependent Mixed Ionic-Electronic Transport in a Perylenediimide Small-Molecule Semiconductor.

A rapidly growing interest in organic bioelectronic applications has spurred the development of a wide variety of organic mixed ionic-electronic conductors. While these new mixed conductors have enabled the community to interface organic electronics with biological systems and efficiently transduce biological signals (ions) into electronic signals, the current materials selection does not offer sufficient selectivity towards specific ions of biological relevance without the use of auxiliary components such as ion-selective membranes. Here, we present the molecular design of an n-type (electron-transporting) perylene diimide semiconductor material decorated with pendant oligoether groups to facilitate interactions with cations such as Na+ and K+. Using the cyclic 15-crown-5 oligoether motif, we find that the resulting mixed conductor PDI-crown displays a strong dependence on the size of the electrolyte cation when tested in an organic electrochemical transistor configuration. In stark contrast to the low current response on the order of 1 μA observed with aqueous sodium chloride, a nearly 200-fold increase in current is observed with aqueous potassium chloride. We ascribe the high selectivity to extended molecular aggregation and therefore efficient charge transport in the presence of K+ due to a favourable sandwich-like structure between two adjacent 15-crown-5 motifs and the potassium ion.

Suppressed Thermal Quenching via Tetrafluoroborate-Induced Surface Reconstruction of CsPbBr3 Nanocrystals for Efficient Perovskite Light-Emitting Diodes.

Although metal-halide perovskite nanocrystals (NCs) have garnered significant attention for optoelectronic applications, the presence of electrically insulating organic ligands in CsPbBr3 NCs hinders efficient charge injection and transportation in light-emitting diodes (LEDs). A common approach to address this issue involves ligand exchange with shorter ligands and precise control of the surface ligand density through additional purification steps. Nevertheless, the practical application of these methods has been hindered by their poor structural integrity and high surface-defect density, which remain a challenge. Our investigation reveals that NOBF4 treatment effectively replaces native ligands with BF4- anions, in which BF4- anions are readily coordinated with the positively charged CsPbBr3 surface metal centers, thereby improving the photoluminescence quantum yield (PLQY) and thermal stability. In particular, the presence of BF4- anions coordinated at CsPbBr3 surfaces efficiently suppresses the pathway of excitons toward thermally activated nonradiative recombination, leading to minimal thermal quenching and superior device performance in green-emitting PeLEDs. Notably, PeLEDs based on CsPbBr3 NCs with the reconstructed surface via NOBF4 treatment exhibit an improved current efficiency of 31.12 cd/A and an external quantum efficiency of 11.24%, increased by 2.8 times compared to that of the pristine sample, indicating the enhanced hole-electron injection and transport into the CsPbBr3 NCs. Therefore, our results highlight the potential of NOBF4 as a versatile reagent for the ligand exchange and surface passivation of CsPbBr3 NCs, thereby offering promising prospects for the development of stable, high-performance PeLEDs.

Construction of Co-CN as a high-performance catalyst for photocatalytic tetracycline degradation and mechanism study

Constructing highly efficient and stable catalysts for tetracycline degradation is very important in avoiding harm to human and ecosystem health. Herein, we doped Co-MOF into carbon nitride (CN) and synthesized successfully a copolymer Co-CN with heterojunctions structure simple intramolecular doping. Various characterization results demonstrate that Co2+ cations are highly dispersed on the CN support. The Co-CN catalyst exhibited outstanding degradation efficiency and recycle stability for tetracycline (TC) degradation, demonstrates a degradation efficiency of 85.2% under benign conditions. Various characterization results revealed the pathway and mechanism of TC degradation. An intramolecular heterojunction structures in Co-CN copolymers promote charge separation and transport efficiency, which make a variety of active species to be generated in the reaction system. Free radical trapping experiment results show that four active species including h+, 1O2, ·O2− and ·OH synergistically catalyze to activate the substrate to achieve degradation of TC molecules.

Interfacial Modification of ZnO/ZnMgO Bilayer for Efficient and Stable InP Quantum Dot Light-Emitting Diodes via Ultraviolet Ozone Treatment.

The development of efficient charge transport layers is crucial for realizing high-performance and stable quantum dot light-emitting diodes (QD-LEDs). The use of a ZnO/ZnMgO bilayer as an electron transporting layer (ETL) has garnered considerable attention. This configuration leverages the high electron mobility of ZnO and the favorable surface state of ZnMgO. Furthermore, the versatility of this configuration extends to its wide range of thickness tunability, rendering it suitable for the construction of thick devices for top-emitting structures with microcavities. However, despite the promising attributes of this bilayer configuration, the impact of the ZnO/ZnMgO bilayer ETL interface on QD-LEDs performance remains largely unexplored. Thus, this study investigated the effect of ultraviolet ozone (UVO) treatment on the stabilization of the ZnO/ZnMgO interface. UVO treatment was found to significantly enhance luminance uniformity across the QD-LEDs emission area while improving operational stability by over 4-fold. Comprehensive analyses employing X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy confirmed that UVO treatment significantly reduced the defect states of the hydroxyl groups and removed the insulating native ethanolamine ligands, thereby facilitating improved and uniform electron transport. Moreover, the effectiveness of UVO treatment in enhancing electron transport was supported by impedance analyses. Therefore, this paper presents an effective approach for enhancing the interface of a highly potent ZnO/ZnMgO bilayer ETL, which can ultimately improve the luminance uniformity and stability of QD-LEDs.

Ethanol Processable Inorganic-Organic Hybrid Hole Transporting Layers Enabled 20.12 % Efficiency Organic Solar Cells.

In this study, a high-performance inorganic-organic hybrid hole transporting layer (HTL) was developed using ethanol-soluble alkoxide precursors and a self-assembled monolayer (SAM). Three metal oxides-vanadium oxide (VOx), niobium oxide (Nb2O5), and tantalum oxide (Ta2O5)-were synthesized through successive low-temperature (100 °C) thermal annealing (TA) and UV-ozone (UVO) treatments of their respective precursors: vanadium oxytriethoxide (EtO-V), niobium ethoxide (EtO-Nb), and tantalum ethoxide (EtO-Ta). Among these, the Nb2O5 film exhibited excellent transmittance, a high work function, and good conductivity, along with a more compact and uniform structure featuring fewer interfacial defects, which facilitated efficient charge extraction and transport. Furthermore, the deposition of a SAM of (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) on top of Nb2O5 further passivated defects, enhancing interfacial contact with the photoactive layer. The resulting inorganic-organic hybrid HTL of Nb2O5/2PACz demonstrated excellent compatibility with various photoactive blends, achieving impressive power conversion efficiencies of 19.44 %, 19.18 %, and 20.12 % for the PM6:L8-BO, PM6:BTP-eC9, and D18:BTP-eC9 based organic solar cells, respectively. 20.12 % is the best performance for bulk heterojunction organic solar cells with binary components as the photoactive layer.

Efficient and stable perovskite solar cells based on multi-active sites 5-amino-1,3,4-thiadiazole-2-thiol modified interface

The highest certification efficiency of perovskite solar cells (PSCs) has reached 26.7 %. However, the high defect density on the surface of perovskite films prepared by low temperature solution method and the energy mismatch between the carrier transport layers and perovskite layer (PVK) greatly limit the performance improvement of PSCs. The introduction of passivating agent to modify the perovskite interface and grain boundary can reduce the defect density, coordinate the energy level effectively, and improve the efficiency and stability of devices. A Lewis base molecule 5-amino-1,3,4-thiadiazole-2-thiol (AMTD) with multiple active sites is introduced at the interface between PVK and hole transport layer (HTL). The electron-rich groups, such as = S, –S–, –NH2, –N on AMTD, passivate the positive electrical defects on the interface and grain boundary, and increase carrier transport efficiency. The interfacial energy level array is optimized to achieve more efficient charge transportation. In addition, the modified of AMTD has a significant protective effect on the perovskite, which inhibit the moisture erosion of in environment. Consequently, the AMTD-optimized device achieves a power conversion efficiency (PCE) of 24.13 %, compared to the efficiency of 21.62 % for pristine device. The stability of the devices is improved greatly.

Endgroup engineering of the third component for high-efficiency ternary organic solar cells

In this study, we carefully designed and synthesized three A-D-A type molecules, namely YF-C8-CN, YF-C8-S, and YF-C8-O. These molecules feature a 2,2′-bithiophene core, which bears two 2,4,6-tripropylbenzene steric hindrance groups, as the central electron-donating unit, and utilize rhodanine (Rh), thiazolidinedione, and dicyanoyl-modified benzotriazole (BTA) respectively as the electron acceptor unit (A-unit). We investigated their impact as the third component on the performance of ternary organic solar cells (OSCs). Our studies indicate that YF-C8-S, with rhodanine terminal groups, exhibits complementary absorption characteristics and cascaded energy levels when combined with the host binary system (D18:eC9-4F). Compared to YF-C8-CN and YF-C8-O, ternary OSCs based on YF-C8-S demonstrate significantly higher exciton diffusion and charge transport efficiency, favorably impacting the short-circuit current density (JSC) and fill factor (FF) of the OSCs. Furthermore, devices based on YF-C8-S exhibit reduced non-radiative energy loss, contributing to an enhanced open-circuit voltage (VOC). Consequently, ternary OSCs based on YF-C8-S achieve a remarkable efficiency of 19.12%, positioning it among the highest reported values. This comprehensive research on the third component of the YF-C8 series underscores their significant potential for fabricating high-performance ternary OSCs.