Reduced Charge Recombination Research Articles

High Efficiency (>10%) AgBiS2 Colloidal Nanocrystal Solar Cells with Diketopyrrolopyrrole-Based Polymer Hole Transport Layer.

Silver bismuth disulfide (AgBiS2) colloidal nanocrystals (CNCs) have emerged as ecofriendly photoactive materials with excellent photoconductivity and high absorption coefficients, in compliance with the restriction of hazardous substances (RoHS) guidelines. To maximize the theoretical potential of AgBiS2 CNC solar cells, a new diketopyrrolopyrrole (DPP)-based polymer, BD2FCT, optimized as a hole transport layer (HTL), is developed. This asymmetric thiophene-rich polymer HTL effectively complements the optical absorption spectrum of CNCs and forms a homogeneous layer atop the CNCs, facilitating favorable vertical charge transfer through intrinsic molecular packing. Furthermore, the BD2FCT HTL aligns energetically with AgBiS2, significantly reducing charge recombination at the CNC/HTL interfaces and enhancing charge extraction and photocurrent generation across the entire optical absorption spectrum. These characteristics are further optimized through precise molecular engineering. Additionally, a low-bandgap acceptor, IEICO-4F, is structurally incorporated with the BD2FCT polymer to further improve charge funneling and complementary absorption. Transient absorption spectroscopy reveals enhanced hole transfer from CNC to BD2FCT-29DPP:IEICO-4F, resulting in reduced charge recombination and efficient charge extraction. Consequently, a BD2FCT-based AgBiS2 CNC solar cell achieves a power conversion efficiency (PCE) of 10.1%, demonstrating significant improvements in short-circuit current density (JSC) and fill factor (FF).

Tuning of the Polymeric Nanofibril Geometry via Side-Chain Interaction toward 20.1% Efficiency of Organic Solar Cells.

Constructing fibril morphology has been believed to be an effective method of achieving efficient exciton dissociation and charge transport in organic solar cells (OSCs). Despite emerging endeavors on the fibrillization of organic semiconductors via chemical structural design or physical manipulation, tuning of the fibril geometry, i.e., width and length, for tailored optoelectronic properties remains to be studied in depth. In this work, a series of alkoxythiophene additives featuring varied alkyl side chains connected to thiophene are designed to modulate the growth of fibril aggregates in cutting-edge polymer donors PM6 and D18. Molecular dynamics simulations and morphological characterizations reveal that these additives preferentially locate near and entangle with the side chains of polymer donors, which enhance the conjugated backbone stacking of polymer donors to form nanofibrils with the width expanding from 12.6 to 21.8 nm and the length increasing from 98.3 to 232.7 nm. This nanofibril structure is feasible to acquire efficient exciton dissociation and charge transport simultaneously. By integrating the fibril PM6 and L8-BO as the donor and acceptor layers in pseudo-bulk heterojunction (p-BHJ) OSCs via layer-by-layer deposition, an improvement of power conversion efficiency (PCE) from 18.7% to 19.8% is observed, contributed by enhanced light absorption, charge transport, and reduced charge recombination. The versatility of these additives is also verified in D18:L8-BO OSCs, with enhanced PCE from 19.3% to 20.1%, which is among the highest values reported for OSCs.

Efficient Light-Driven Ion Pumping for Deep Desalination via the Vertical Gradient Protonation of Covalent Organic Framework Membranes.

Traditional desalination methods face criticism due to high energy requirements and inadequate trace ion removal, whereas natural light-driven ion pumps offer superior efficiency. Current synthetic systems are constrained by short exciton lifetimes, which limit their ability to generate sufficient electric fields for effective ion pumping. We introduce an innovative approach utilizing covalent-organic framework membranes that enhance light absorption and reduce charge recombination through vertical gradient protonation of imine linkages during acid-catalyzed liquid-liquid interfacial polymerization. This technique creates intralayer and interlayer heterojunctions, facilitating interlayer hybridization and establishing a robust built-in electric field under illumination. These improvements enable the membranes to achieve remarkable ion transport across extreme concentration gradients (2000:1), with a transport rate of approximately 3.2 × 1012 ions per second per square centimeter and reduce ion concentrations to parts per billion. This performance significantly surpasses that of conventional reverse osmosis systems, representing a major advancement in solar-powered desalination technology by substantially reducing energy consumption and secondary waste.

Improving Photocatalytic Hydrogen Production with Sol–Gel Prepared NiTiO₃/TiO₂ Composite

This study presents a comprehensive investigation into the synthesis, characterization, and photocatalytic performance of NiTiO3/TiO2 nanocomposites for solar hydrogen production. Through a carefully optimized sol–gel method, we synthesized a heterojunction photocatalyst comprising 99.2% NiTiO3 and 0.8% anatase TiO2. Extensive characterization using XRD, Raman spectroscopy, FTIR, UV–visible spectroscopy, photoluminescence spectroscopy, and TEM revealed the formation of an intimate heterojunction between rhombohedral NiTiO3 and anatase TiO2. The nanocomposite demonstrated remarkable improvements in optical and electronic properties, including enhanced UV–visible light absorption and an 85% reduction in charge carrier recombination compared to pristine NiTiO3. Crystallite size analysis showed a reduction from 53.46 nm to 46.35 nm upon TiO2 incorporation, leading to increased surface area and active sites. High-resolution TEM confirmed the formation of well-defined interfaces between NiTiO3 and TiO2, with lattice fringes of 0.349 nm and 0.249 nm corresponding to their respective crystallographic planes. Under UV irradiation, the NiTiO3/TiO2 nanocomposite exhibited superior photocatalytic performance, achieving a hydrogen evolution rate of 9.74 μmol min−1, representing a 17.1% improvement over pristine NiTiO3. This enhancement is attributed to the synergistic effects of improved light absorption, reduced charge recombination, and efficient charge separation at the heterojunction interface. Our findings demonstrate the potential of NiTiO3/TiO2 nanocomposites as efficient photocatalysts for solar hydrogen production and contribute to the development of advanced materials for renewable energy applications.

Fluorine/bromine/selenium multi-heteroatoms substituted dual-asymmetric electron acceptors for o-xylene processed organic solar cells with 19.12% efficiency

AbstractThe development of high-performance near-infrared (NIR) absorbing electron acceptors is a major challenge in achieving high short-circuit current density (JSC) to increase power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, three new multi-heteroatomized Y-series acceptors (bi-asy-Y-Br, bi-asy-Y-FBr, and bi-asy-Y-FBrF) were developed by combining dual-asymmetric selenium-fused core and brominated end-groups with different numbers of fluorine substitutions. With gradually increasing fluorination, three acceptors exhibit red-shift absorption. Among them, bi-asy-Y-FBrF presents planar molecular geometry, the maximum average electrostatic potential, and the minimum molecular dipole moment, which are conducive to intramolecular packing and charge transport. Moreover, D18:bi-asy-Y-FBrF active layer presents higher crystallinity, more suitable phase separation, and reduced charge recombination compared to D18:bi-asy-Y-Br and D18:bi-asy-Y-FBr blends. Consequently, among theses binary OSCs, D18:bi-asy-Y-FBrF device achieves a higher PCE of 15.74% with an enhanced JSC of 26.28 mA cm−2, while D18:bi-asy-Y-Br device obtains a moderate PCE of 15.04% with the highest open-circuit voltage (VOC) of 0.926 V. Inspired by its high VOC and complementary absorption with NIR-absorbing BTP-eC9 as acceptor, bi-asy-Y-Br is introduced into binary D18:BTP-eC9 to construct ternary OSCs, achieving a further boosted PCE of 19.12%, which is among the top values for the reported green solvent processed OSCs.

FAPbI3-nanoparticles with ligands act synergistically in absorbent layers for high-performance and stable FAPbI3 based perovskite solar cells

The performance of perovskite solar cells (PSCs) depends on the quality of the perovskite absorber layer. In this study, oleic acid (OA) and oleylamine (OAm) ligand-capped formamidinium lead iodide (FAPbI3) nanoparticles (NPs) were incorporated into the formamidinium iodide (FAI) solution, which is one of the precursors for the sequential deposition of the FAPbI3 layer. The synergistic effect of the FAPbI3-NPs and the capped ligand substantially improves the crystallinity, uniformity, and morphology of the bulk FAPbI3 perovskite films. The enhancements lead to a reduction in charge recombination and a boost in charge transfer efficiency, enabling the optimized PSCs to achieve a remarkable peak power conversion efficiency (PCE) of 25.68 %. Moreover, these PSCs show good stability, with unencapsulated devices maintaining 93 % of the peak performance under ambient air (RH 50 %) for 1000 hours.

Construction of Bi2MoO6 sheets/NH2-UiO-66(Zr) heterojunction photocatalysts toward enhanced degradation of tetracycline under visible light

The application of photocatalysts in environmental field has emerged as a prominent research topic. Nevertheless, the efficiency of photocatalysts is reduced as the recombination of photogenerated chargers significantly, restricting their extensive use in this domain. In the present study, photocatalysts composed of bismuth molybdate/NH2-UiO-66(Zr) (Bi2MoO6/NH2-UiO-66(Zr)) featuring Z-scheme heterojunctions were effectively synthesized using a two-step hydrothermal technique. These photocatalysts exhibit remarkable photocatalytic degradation under visible light conditions. Notably, the broad planar configuration of Bi2MoO6 sheets improves the separation of the photogenerated charge carriers. NH2-UiO-66(Zr) layered atop Bi2MoO6 sheets enhances the availability of catalytically active sites, reduces charge recombination, and promotes charge transfer through the interface. The kinetic rate constant for Bi2MoO6/NH2-UiO-66(Zr) is around 0.00329 L mg−1 min−1, indicating the increase of 3.78 and 41.13 times compared with pure Bi2MoO6 and NH2-UiO-66(Zr), respectively. The efficiency for photocatalytic degradation of tetracycline using Bi2MoO6/NH2-UiO-66(Zr) reaches 81.72 % under visible light. Importantly, this efficiency exhibits a reduction of 10 % after five recycling cycles, demonstrating notable stability. The photocatalytic mechanism involved in tetracycline degradation was uncovered through trapping experiments and EPR, indicating that it is predominantly facilitated by the active oxidation of ·O2- and ·OH. The intermediates of the photocatalytic process as well as the possible degradation pathways were discussed. The creation of Bi2MoO6 sheets/NH2-UiO-66(Zr) heterojunction photocatalysts provides a fresh approach to the development of novel catalysts, which may lead to significant advancements in environmental remediation efforts.

Rational Design of Two Well‐Compatible Dimeric Acceptors Through Regulating Chalcogen‐Substituted Conjugated Backbone Enable Ternary Organic Solar Cells with 19.4% Efficiency

AbstractTo enhance the performance of dimeric acceptors (DMAs) based organic solar cells (OSCs), two new DMAs, designated as DC9‐HD and DYSe‐3, are rationally developed and employed to fabricate ternary OSCs. The substitution of the sulfur atom on the outer ring of the fused‐ring core of DC9‐HD with a selenium atom resultes in the red‐shifted DYSe‐3. Despite these minor differences, DC9‐HD and DYSe‐3 possess nearly identical conjugated skeletons, which contribute to their similar packing motifs and crystallinities, ultimately enabling a high degree of miscibility between two DMAs. Upon incorporating DYSe‐3 into the host PM6:DC9‐HD binary blend, fibril‐like morphologies featured with diameters of ≈16.9 nm and reduced charge recombination are observed in the PM6:DC9‐HD:DYSe‐3 ternary blend. More importantly, owing to their long exciton diffusion lengths and low voltage losses, a remarkable power conversion efficiency of 19.4% is achieved for the ternary OSCs, alongside a delicate balance between open‐circuit voltage and short‐circuit current density. This super result is comparable to the best performance of oligomer acceptor based OSCs reported to date. Furthermore, the proposed ternary strategy, which combines one polymer donor and two well‐compatible DMAs, not only retains the advantages of DMAs but also offers a streamlined approach for fabricating high‐performance ternary OSCs.

Exceeding 23% Efficiency for 3D/3D Bilayer Perovskite Heterojunction MAPbI3/FAPbI3‐Based Hybrid Perovskite Solar Cells with Enhanced Stability

AbstractOrganic–inorganic hybrid perovskite solar cells (HPSCs) are gaining attention as a promising technology for next‐generation photovoltaic devices owing to their impressive power conversion efficiency (PCE) and cost‐effective fabrication methods. Although, solution‐processed passivation using 2D perovskites can improve the interface recombination, this approach hampers its effective charge transportation. In this study, the study investigates the properties and performance of the bilayer 3D/3D methylammonium lead iodide (MAPbI3)/formamidinium lead iodide (FAPbI3)‐based perovskite heterojunction (BPHJ) to address these concerns. The bilayer structure consists of two distinct perovskite absorbers having independent structure that are sandwiched between two charge transporting layer (CTLs) to make functional device. First, the fabrication process is optimized to achieve high‐quality MAPbI3 perovskite films with controlled morphology and crystallinity followed by the formation of BPHJ using FAPbI3 deposition by thermal evaporation technique. The BPHJ‐160 nm‐based PSCs with optimized parameters exhibit an enhanced PCE of 23.08% compared to single‐layer reference (20.15%) device. The improved performance can be attributed to the effective charge extraction at the heterojunction interface and reduced charge recombination losses due to favorable energy levels. Furthermore, the long‐term stability of the BPHJ‐based perovskite device is assessed under continuous illumination along with its ambient and thermal stability across different environmental conditions.

Regiospecific Incorporation of Fluorine Atoms in Polythiophene Derivatives for Efficient Organic Solar Cells.

Derivatives of polythiophene (PT) have garnered considerable attention in organic solar cells (OSCs) because of their relatively uncomplicated molecular structures and cost-effective synthesis. Herein, we have developed two regioisomeric fluorinated PT donors, PEI3T-FITVT and PEI3T-FOTVT, to realize efficient OSCs. PEI3T-FITVT and PEI3T-FOTVT are strategically designed with different fluorine atom arrangements on thiophene-vinyl-thiophene (TVT) units. Notably, PEI3T-FOTVT possesses enhanced backbone planarity induced by F···S noncovalent interactions between two constituent building blocks. Consequently, PEI3T-FOTVT with the higher aggregation and crystalline properties leads to a 2.5-fold increase in hole mobility over PEI3T-FITVT (from 1.4 × 10-4 to 3.6 × 10-4 cm2 V-1 s-1). Furthermore, PEI3T-FOTVT exhibits higher domain purity than PEI3T-FITVT, leading to faster charge transport and reduced charge recombination in OSC devices. These characteristics lead to a higher power conversion efficiency of 14.4% for PEI3T-FOTVT-based OSCs, compared to 12.9% for PEI3T-FITVT-based OSCs.

Tetrabutylammonium Hydroxide-Functionalized Ti3C2Tx MXene for Significantly Improving the Photovoltaic Performance of Perovskite Solar Cells.

An appropriate electron transport layer (ETL) or cathode buffer layer (CBL) is critical for high-performance perovskite solar cells (PVSCs). In this work, tetrabutylammonium hydroxide (TBAOH)-functionalized Ti3C2Tx MXene (TBAOH-Ti3C2Tx) is developed to improve the photovoltaic performance of PVSCs. TBAOH-Ti3C2Tx is synthesized by HF etching and then TBAOH intercalation, and TBAOH can effectively attach to the Ti3C2Tx surface during the intercalation process. In hole transport material (HTM)-free carbon-based PVSCs with the structure of ITO/ETL/MAPbI3/carbon, the SnO2 doped by TBAOH-Ti3C2Tx (SnO2:TBAOH-Ti3C2Tx) as ETL shows decreased WF and increased conductivity and improves the growth of the perovskite film with a larger grain and significantly reduced defects, which synergistically facilitate charge transport and extraction and reduce charge recombination. The HTM-free carbon-based PVSC with SnO2:TBAOH-Ti3C2Tx ETL exhibits a significantly higher PCE of 14.93% with enhanced device stability compared to the control device with pristine SnO2 ETL (11.95%) and also outperforms most of the HTM-free carbon-based PVSCs with MAPbI3 perovskite reported so far. In traditional inverted PVSCs with the structure of ITO/PTAA/MAPbI3/PCBM/CBL/Ag, the TBAOH-Ti3C2Tx is utilized as a CBL to significantly enhance device performance with a high PCE of 21.16%, which is obviously superior than that (16.26%) of the control device without CBL. The impressive results indicate that tetrabutylammonium hydroxide-functionalized Ti3C2Tx MXene possesses great application potential in different functional layers for high-performance PVSCs.

Composition design of fullerene-based hybrid electron transport layer for efficient and stable wide-bandgap perovskite solar cells

Fullerene derivatives [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) has been routinely used as the electron transport layer (ETL) in perovskite solar cells due to its suitable energy levels and good solution processability. However, its electron mobility and conductivity still need to be further enhanced for constructing high performance perovskite solar cells (PSCs). Herein, by doping the PC61BM with a p-type polymer PM6 and n-type molecule ITIC, efficient wide-bandgap perovskite solar cells with improved efficiency and operational/storage stability are obtained. Further spectroscopy and electric measurements indicate PM6 and ITIC can both passivate defects at the perovskite/ETL interface, meanwhile ITIC can elevate the Fermi level of PC61BM to enhance conductivity and PM6 can improve the photo-induced electron mobility of the ETL, facilitating charge extraction and reducing charge recombination. As the results, Cs0.17FA0.83Pb(I0.83Br0.17)3 wide-bandgap PSCs with PM6:PC61BM:ITIC as the ETL demonstrates a superior efficiency of 22.95%, compared to 20.89% of the PC61BM assisted device.

Self‐Induced Bi‐interfacial Modification via Fluoropyridinic Acid For High‐Performance Inverted Perovskite Solar Cells

AbstractThe uncontrolled crystallization of perovskite generates a significant number of internal and interfacial defects, posing a major challenge to the performance of perovskite solar cells (PSCs). In this paper, a novel bi‐interfacial modification strategy utilizing 5‐fluoropyridinic acid (FPA) is proposed to modulate crystal growth and provide defect passivation. It is demonstrated that FPA is self‐deposited at both the top and bottom interfaces of perovskite films during thermal annealing. The CO and N functional groups in FPA serve as chelating agents, binding closely to uncoordinated Pb2+/Pb clusters, thereby passivating defects and reducing charge recombination at the interfaces. The strong chemical interactions between FPA and Pb further stabilize the Pb‐I framework, promoting the formation of high‐quality perovskite films, as confirmed by in situ photoluminescence measurements. Consequently, the modified inverted PSCs achieved an exceptional power conversion efficiency (PCE) of 25.37%. Moreover, the devices retained over 93.17% of initial efficiency after 3000 h of continuous illumination under one‐sun equivalent conditions in a nitrogen atmosphere. This paper presents a promising pathway for enhancing the performance and stability of inverted PSCs through a self‐induced bi‐interfacial modification approach.

Enhancing photocatalytic water treatment efficiency via nitrogen Self-Doping and Hive-Like Structuring in isotype homojunctions of g-C3N4 generated from Thiourea-Melamine copolymerization

The combination of overpopulation and rapid industrial progress has led to a pronounced increase in water contamination. Photocatalysis emerges as a viable solution for mitigating water pollution, and graphitic carbon nitride (g-C3N4) is considered as a particularly promising photocatalyst due to its advantageous properties, such as low cost, and high chemical stability. Nonetheless, the effectiveness of g-C3N4 is often compromised by its limited surface area and substantial recombination of photogenerated charge carriers. To address these challenges, in this work, we propose a systematic approach to develop photocatalytically efficient surface structures and intimate isotype homojunctions through the copolymerization of various g-C3N4 precursors. A range of photocatalysts, each with distinctly tailored morphologies and homojunctions, was produced and their photocatalytic performance was assessed through the removal efficiencies of model pollutants, bisphenol A (BPA), and methylene blue (MB), with each at a concentration of 10 mg L-1. The enhanced photocatalytic activity observed in the optimized sample is primarily attributed to its significantly increased surface area, which is ten times greater than that of standard g-C3N4, and a marked reduction in charge recombination, which is four times lower, facilitated by the intimate homojunction. Thus, this work will open the door to the synthesis of various highly efficient photocatalysts for application in the photodegradation of diverse pollutants, consequently mitigating adverse environmental effects.

A Diphosphonic Acid-Based Interlayer for Highly Efficient and Stable Inverted Perovskite Solar Cells.

We investigate an interlayer of 6,6'-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-[1,1'-binaphthalene]-(2,2'-diyl)bis(oxy)bis(propane-3,1-diyl)bis(phosphonic acid) (BINOL-PA) with undoped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) coverage. The incorporation of the 1,10-bi-2-naphthol central core enhances π-π stacking and reduces charge recombination at the interface. Compared to PTAA alone (0.95 eV), BINOL-PA/PTAA exhibits a shorter distance from the Fermi energy (EF) to the valence-band maximum (VBM) (0.36 eV). Two phosphoric acid units in BINOL-PA fine-tune the molecular dipoles. Theoretical calculations reveal electrostatic surface potential differences between BINOL-PA and PTAA in their backbone structure. Open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS) results suggest suppressed interface recombination. The photovoltaic conversion efficiency (PCE), short-circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF) for the BINOL-PA/PTAA device are measured as 21.02%, 22.67 mA cm-2, 1.12 V, and 82.8%, respectively, all higher than those achieved by the PTAA device with a PCE of 18%. BINOL-PA/PTAA significantly elevates VOC and FF values compared with dopant-free PTAA alone. The champion device retains over 89% of its initial PCE after being exposed to an ambient environment without encapsulation for more than 30 days. The thermal aging test conducted under a nitrogen atmosphere demonstrates that the efficiency retention rate for BINOL-PA/PTAA displays 60% of its initial efficiency after 1500 h.

Revolutionizing dye-sensitized solar cells: Chassalia curviflora fruit extract as photosensitizer and charge recombination inhibitor

The utilization of natural dyes from Chassalia curviflora (CCE), which were successfully extracted to provide bioactive chemicals for the development of dye-sensitized solar cells (DSSCs), is the main focus of this work. These CCEs efficiently absorb light and stop charge recombination in solar cells after being extracted using ethanol. The absorption properties of these natural dyes are discovered to be greatly influenced by the kind and concentration of CCE, with an absorption peak observed at 350 nm. The dyes’ improved adsorption properties on TiO2 are indicated by the presence of functional groups, bond stretching, and bending features, as confirmed by FTIR and UV–Visible spectroscopic investigations. In the DSSC design, these dyes have been effectively combined with an FTO substrate covered with TiO2, serving as a photoanode. The resultant solar cells, which comprise a graphite-based counter electrode, I−/I3− electrolyte, and photoanode, have a power conversion efficiency (PCE) of 0.49 %. The measurements for fill factor, Voc, and Jsc are 0.4761, 1.652 mA/cm2, and 0.52 V, in that order. The phytochemical components of the dye are shown to be crucial in trapping electrons and holes, hence reducing charge recombination and promoting enhanced charge transport towards the titanium dioxide transmission group finding is noteworthy. Furthermore, a dipping time analysis reveals that a 15-minute duration is optimal for achieving a 0.146 % photoelectric conversion efficiency in DSSCs utilizing CCE.

How to choose proper electron acceptor groups for highly efficient copper electrolyte-based dye-sensitized solar cells?

A better understanding of electron-accepting groups (EAGs) is important for the development of potentially efficient dyes. Density functional theory (DFT) and time-dependent DFT were employed in this study to investigate a variety of dyes derived from XY1b (11.8 %) in conjunction with prominent EAGs including 2-cyano-3-phenylacrylic acid (CPA), 2-cyano-acrylic acid (CA), and benzoic acid (BA). Various critical parameters pertaining to short-circuit current density (Jsc) and open-circuit photovoltage (Voc) were calculated, including light-harvesting ability, conduction band energy shift, dye-[Cu(tmby)2]2+ interaction, dye aggregation, and charge recombination, in order to illustrate the advantages and limitations of these EAGs. The findings indicate that dyes based on CA demonstrate a redshifted absorption spectrum, stronger electronic coupling with TiO2 conduction band, extended excited state lifetime, and enhanced dye regeneration driving force, resulting in higher Jsc compared to CPA and BA-based dyes. Regarding Voc, CA-based dyes show an increased conduction band energy shift due to their larger vertical dipole moment and reduced charge recombination with [Cu(tmby)2]2+. Additionally, it is suggested that future studies on structure–property relationships should prioritize identifying the optimal dye conformation, as it significantly influences adsorption configuration and vertical dipole moment. Overall, among the commonly utilized EAGs, CA stands out for its ability to enhance Jsc, Voc, and adsorption stability over CPA and BA-based dyes.

Optimizing electron transport layers for high-efficiency perovskite solar cells using impedance spectroscopy

The best interface for a perovskite solar cell is designed to facilitate effective charge transport to achieve a high-power conversion efficiency. Tin dioxide (SnO2) is widely recognized as an electron transport material for perovskite solar cells, offering advantages such as low hysteresis, low defect concentration, and low fabrication temperature. However, the low conduction band edge of SnO2 restricts the built-in potential of the solar cell device. In this study, we designed a double layer of electron transport by applying zinc oxide (ZnO) on SnO2 to improve the electron transport properties in perovskite solar cells. The bilayer of electron transport enhances the interfaces between the perovskite and the electron transport layer, leading to an improvement in the efficiency and stability of solar cell devices up to 11.71 % compared to a single SnO2 layer device with a PCE of 9.06 %. The introduction of ZnO reduces charge recombination, resulting in a lower recombination resistance (Rrec). Also, charge transfer resistance (Rct) of ZnO/SnO2 increased to 16.6KΩ compared to a single SnO2 layer device with a Rct of 5.29KΩ. Our findings provide valuable insights into the design of electron transport layers for perovskite solar cells and highlight the importance of electrochemical impedance spectroscopy in understanding the dynamic processes that govern their performance.

A Spin‐Polarized Electron‐Induced MXene‐KBi0.9Co0.1Fe2O5 Photocatalyst for Enhanced Dye Degradation

In photocatalysts aimed to degrade environmental pollutants, photons are generally used as primary stimuli to generate electron–hole pairs to target the chemical bonds to disintegrate. Recently, electron spin has been reported as an essential degree of freedom to improve the performance of photocatalysts. In this work, spin‐polarized electrons and holes are introduced into a brownmillerite KBi0.9Co0.1Fe2O5 semiconductor and a two‐dimensional (2D) MXene composite system by application of an external magnetic field. The spin polarization properties are monitored by measuring the magnetoresistance effect of the MXene‐KBCFO device, which is related to the carrier transfer efficiency. Remarkably, the photocatalytic performance of MXene‐KBCFO is significantly enhanced by the simultaneous application of an external magnetic field and illumination due to the increased number of spin‐polarized photoexcited carriers caused by the synergy effect of the 2D MXene heterostructure together with the ferromagnetic spin ordering. This results in increased reaction hotspots, effective built‐in electric field, extended carrier lifetime, and reduced charge recombination owing to parallel alignment of electron spin orientation. The results show that the efficiency and stability of photocatalytic dye degradation can be effectively enhanced by manipulating the spin‐polarized electrons in the MXene‐based oxide‐perovskite heterostructure photocatalyst.

Performance analysis and optimization of SnSe thin-film solar cell with Cu2O HTL through a combination of SCAPS-1D and machine learning approaches

Tin selenide (SnSe) is an auspicious light-harvesting material in photovoltaic (PV) technology due to its larger absorption coefficients and earth-abundance nature. However, because of the potential difficulty of defect-free fabrication, and non-optimized electron transport layer (ETL) and hole transport layer (HTL) alignment, it could no longer achieve its realistic objectives. Therefore, designing a suitable SnSe-based PV device with an appropriate ETL and HTL is crucial to achieving optimum performance. In this research, we proposed a novel heterojunction thin-film solar cell (TFSC) configuration of Ni/Cu2O/SnSe/WS2/FTO/Al and simulated its PV performance metrics using SCAPS-1D solar cell simulation software. This research additionally provided a comparative performance analysis of the SnSe TFSC with numerous ETLs and HTLs. It is evident that the suggested TFSC with WS2 ETL and Cu2O HTL creates appropriate band alignment with the SnSe light harvesting layer, which reduces charge recombination at both the ETL/absorber and absorber/HTL interfaces. Here, the impact of absorber layer thickness, doping concentration, bulk defect density, and defect density at the ETL/absorber and absorber/HTL interfaces is investigated. Besides, the impact of radiative recombination, back contact metal work function, and working temperature are carefully examined. After optimization of all the material properties, a maximum efficiency of 29.31 % with open circuit voltage (Voc) of 0.89 V, short circuit current density (Jsc) of 38.23 mA/cm2, and fill-factor (FF) of 86.30 % were attained for the SnSe-based proposed structure. Furthermore, a supervised linear regression machine learning algorithm is employed to investigate how the behavior of the material attributes affects the solar cell's designed PV performance. Overall, our findings can be helpful to experimentalists to fabricate inexpensive, highly efficient, and Cd-free SnSe-based heterostructure solar cells in the near future.