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Influence of RbF post deposition treatment on heterojunction and grain boundaries in high efficient (21.1%) Cu(In,Ga)Se2 solar cells
摘要： Post deposition treatments (PDT) by alkali fluorides applied to chalcopyrite-based absorbers have produced record efficiencies in thin-film solar devices in the past few years and recently the efficiency of 22.6 % was achieved with Cu(In,Ga)Se2 (CIGS) using rubidium fluoride (RbF) PDT. However, the effects of RbF-PDT towards changes in its interfacial and grain boundary (GB) properties are still not fully understood. In this work, cells with efficiency higher than 21% are investigated by combination of atom probe tomography (APT) and transmission electron microscopy (TEM) to show how changes in GB and interface chemistry may facilitate high efficiencies. APT studies, carried out at the interface between CIGS absorber and solution-grown CdS buffer layer, show In enrichment and Cu depletion along with traces of Rb. Our APT studies reveal higher amounts of Rb (1.5 at. %) and lower amounts of Na and K (<0.5 at. %) at GBs as compared with previous studies (on non-PDT samples) thus indicating substitution of Na and K by Rb. However, concentration of all alkali elements inside the grain bulk is below detection limit of APT. The concentration of Rb at the GBs in CIGS is measured depth-dependent using both APT and TEM, which consistently shows the increase in Rb towards the Mo back contact. In addition, a pronounced Cu depletion is observed at the GBs which might enhance hole-barrier properties of the GBs, thus improving charge carrier collection and hence the overall efficiency of the device. Thus, understanding effects of RbF-PDT at the atomic scale provides new insights concerning the further improvement of CIGS absorber and interfaces.
关键词： Cu(In,Ga)Se2,Thin-film solar cell,heterojunction,atom probe tomography,post deposition treatments,transmission electron microscopy
更新于2025-11-21 11:20:48
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Fabrication and characterization of lead sulfide (PbS) thin film based heterostructure (FTO/CdS/PbS/Ag) solar cell by nebulizer spray method
摘要： This work deals with the study on the key properties of PbS thin films prepared by simple nebulizer spray method. The structural study done by XRD exhibited cubic crystal structure with polycrystalline nature for the deposited PbS films. The obtained crystallite size was varied between 41 to 55 nm for various molar concentrations. The morphology study done by SEM displays uniform distribution of the grains all over the surface of the prepared PbS thin films. The observed band gap value was decreased from 1.8 eV to 1.51 eV for various molar concentrations. The emitted PL intensity was strong at about 580 nm which is related to the near band edge (NBE) emission. Electrical studies performed by Hall Effect measurement confirm the p-type conductivity of prepared films. Resistivity and carrier concentrations are 2.92×103 Ω-cm and 4.83×1013cm-3 respectively for the deposited films. In addition, a heterojunction solar cell of structure FTO/n-CdS/p-PbS/Ag was produced and its conversion efficiency was ~ 0.39%.
关键词： SEM,PbS,Heterojunction device.,Hall Effect,Photoluminescence
更新于2025-11-21 11:18:25
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Coral-Like Perovskite Nanostructures for Enhanced Light-Harvesting and Accelerated Charge Extraction in Perovskite Solar Cells
摘要： A novel coral-like perovskite nanostructured layer was grown on a compact perovskite foundation layer by the facile surface modification with dimethylformamide/isopropanol (DMF/IPA) as co-solvent. Surface morphological characterizations with SEM and XRD analyses revealed a growing mechanism of the new morphology, which was composed of the perovskite decomposition and recrystallization, excessive-PbI2 extraction, and sequential formation of coral-like nanostructured perovskite layer. The coral-like perovskite nanostructures resulted in significant light scattering, enhancing the light harvesting efficiency, and thus augmenting the photocurrent density. Moreover, the geometric configuration of the perovksite solar cells was changed from planar to bulk heterojunction, which results in the acceleration of charge separation and extraction due to the high surface area at the interface between the obtained perovskite and hole-transport layers. The optimal perovskite solar cell exhibited an impressive power conversion efficiency (PCE) of 19.47%, as compared to that of the pristine cell (17.19%).
关键词： solar cells,Bulk heterojunction,light-harvesting,coral-like nanostructures,surface modification,perovskite
更新于2025-11-21 11:01:37
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Z-scheme Bi2WO6/CuBi2O4 heterojunction mediated by interfacial electric field for efficient visible-light photocatalytic degradation of tetracycline
摘要： In order for the removal of Tetracycline (TC) in wastewaters, an efficient binary Bi2WO6/CuBi2O4 Z-scheme heterojunction photocatalyst was synthesized by loading Bi2WO6 (BWO) nanoparticles on CuBi2O4 (CBO) nanorods via a solvothermal route. The obtained Bi2WO6/CuBi2O4 composite displays photocatalytic activity for TC degradation more than five times higher than that for pure CBO nanorods. The recycling experiment shows that over 91% of TC can be photo-degraded by the optimal Bi2WO6/CuBi2O4 photocatalyst within 60 min even after four cycles. Results of SEM, transient photocurrent response, EIS measurement prove that solvothermal process for BWO loading can introduce rough surface with high-density negative charge on CBO, contributing to effective photo-induced carrier transfer. XPS, Mott?Schottky plots and PL spectra reveal that the loading of BWO as well as interfacial charge redistribution can induce the formation of interfacial electric field for Z-scheme heterojunction, contributing to the high oxidation and reduction capabilities ability of Bi2WO6/CuBi2O4 composite. The study on photocatalytic mechanism discloses that hole (h+) and superoxide radical (?O2?) are dominating reactive oxidation species (ROS) in the photodegradation process. This study has provided a novel route to fabricate Z-scheme photocatalysts for effective photocatalytic degradation processes.
关键词： charge transfer,Z-scheme heterojunction,environmental materials,interfacial electric field,photocatalysis,tetracycline degradation
更新于2025-11-21 10:59:37
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Fusing Nanowires into Thin Films: Fabrication of Graded‐Heterojunction Perovskite Solar Cells with Enhanced Performance
摘要： Perovskite solar cells (PSCs) have recently experienced a rapid rise in power conversion efficiency (PCE), but the prevailing PSCs with conventional mesoscopic or planar device architectures still contain nonideal perovskite/hole-transporting-layer (HTL) interfaces, limiting further enhancement in PCE and device stability. In this work, CsPbBr3 perovskite nanowires are employed for modifying the surface electronic states of bulk perovskite thin films, forming compositionally-graded heterojunction at the perovskite/HTL interface of PSCs. The nanowire morphology is found to be key to achieving lateral homogeneity in the perovskite film surface states resulting in a near-ideal graded heterojunction. The hidden role of such lateral homogeneity on the performance of graded-heterojunction PSCs is revealed for the first time. The resulting PSCs show high PCE up to 21.4%, as well as high operational stability, which is superior to control PSCs fabricated without CsPbBr3-nanocrystals modification and with CsPbBr3-nanocubes modification. This study demonstrates the promise of controlled hybridization of perovskite nanowires and bulk thin films for more efficient and stable PSCs.
关键词： nanocrystals,morphology control,heterojunction,solar cells,halide perovskites
更新于2025-11-20 15:33:11
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Steady Enhancement in Photovoltaic Properties of Fluorine Functionalized Quinoxaline-Based Narrow Bandgap Polymer
摘要： To investigate the influence of fluoride phenyl side-chains onto a quinoxaline (Qx) unit on the photovoltaic performance of the narrow bandgap (NBG) photovoltaic polymers, herein, two novel NBG copolymers, PBDTT-DTQx and PBDTT-DTmFQx, were synthesized and characterized. 2-ethylhexylthiothiophene-substituted benzodithiophene (BDTT), 2,3-diphenylquinoxaline (DQx) [or 2,3-bis(3-fluorophenyl)quinoxaline (DmFQx)] and 2-ethylhexylthiophene (T) were used as the electron donor (D) unit, electron-withdrawing acceptor (A) unit and π-bridge, respectively. Compared to non-fluorine substituted PBDTT-DTQx, fluoride PBDTT-DTmFQx exhibited a wide UV-Vis absorption spectrum and high hole mobility. An enhanced short-circuit current (Jsc) and fill factor (FF) simultaneously gave rise to favorable efficiencies in the polymer/PC71BM-based polymer solar cells (PSCs). Under the illumination of AM 1.5G (100 mW cm?2), a maximum power conversion efficiency (PCE) of 6.40% was achieved with an open-circuit voltage (Voc) of 0.87 V, a Jsc of 12.0 mA cm?2 and a FF of 61.45% in PBDTT-DTmFQx/PC71BM-based PSCs, while PBDTT-DTQx-based devices also exhibited a PCE of 5.43%. The excellent results obtained demonstrate that PBDTT-DTmFQx by fluorine atom engineering could be a promising candidate for organic photovoltaics.
关键词： quinoxaline,synthesis,polymer solar cells,bulk heterojunction,narrow bandgap conjugated polymer
更新于2025-11-19 16:56:42
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Facile Synthesis and Enhanced Visible-Light Photocatalytic Activity of Novel p-Ag3PO4/n-BiFeO3 Heterojunction Composites for Dye Degradation
摘要： In this work, Ag3PO4 microparticles were decorated onto the surface of BiFeO3 microcuboids through a precipitation method to obtain p-Ag3PO4/n-BiFeO3 heterojunction composites. The composites were employed for the degradation of acid orange 7 (AO7) under visible-light irradiation. It is found that the composites exhibit much higher photocatalytic efficiency than bare BiFeO3. Meanwhile, the intrinsical visible-light-driven photocatalytic activity of Ag3PO4/BiFeO3 composites was further confirmed by the degradation of phenol. In addition, the photo-Fenton-like catalysis property of the composite was also evaluated. The photocurrent analysis indicates that the combination of BiFeO3 with Ag3PO4 leads to the inhibition of recombination of photoinduced electrons and holes. The obvious enhancement in the photocatalytic activity of the composite is mainly ascribed to the efficient photogenerated charge separation and interfacial charge migration caused by the formation of Ag3PO4/BiFeO3 p-n heterojunctions.
关键词： BiFeO3,Photocatalysis,Heterojunction,Ag3PO4
更新于2025-11-19 16:46:39
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Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag2S/BiFeO3 Heterojunction Composites under Visible-Light Irradiation
摘要： Z-scheme Ag2S/BiFeO3 heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag2S nanoparticles (30–50 nm) are well-decorated on the surfaces of polyhedral BiFeO3 particles (500–800 nm) to form Ag2S/BiFeO3 heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag2S/BiFeO3 heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag2S/BiFeO3 composites exhibit much improved photocatalytic activities when compared with bare Ag2S and BiFeO3. The optimum composite sample was observed to be 15% Ag2S/BiFeO3 with an Ag2S mass fraction of 15%. Furthermore, the addition of H2O2 can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag2S/BiFeO3 composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag2S/BiFeO3 composites were proposed and discussed.
关键词： polyhedral BiFeO3 particles,photo-Fenton catalysis,Ag2S nanoparticles,photocatalysis,Z-scheme Ag2S/BiFeO3 heterojunction
更新于2025-11-19 16:46:39
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Photoelectrochemical biosensor for microRNA detection based on a MoS2/g-C3N4/black TiO2 heterojunction with Histostar@AuNPs for signal amplification
摘要： Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of microRNA-396a based on a MoS2/g-C3N4/black TiO2 heterojunction as the photoactive material and gold nanoparticles carrying Histostar antibodies (Histostar@AuNPs) for signal amplification. Briefly, MoS2/g-C3N4/black TiO2 was deposited on an indium tin oxide (ITO) electrode surface, after which gold nanoparticles (AuNPs) and probe DNA were assembled on the modified electrode. Hybridization with miRNA-396a resulted in a rigid DNA:RNA hybrid being formed, which was recognized by the S9.6 antibody. The captured antibody can further conjugate with the secondary IgG antibodies of Histostar@AuNPs, thereby leading to the immobilization of horse radish peroxidase (HRP). In the presence of HRP, the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 was accelerated, producing the insoluble product benzo-4-chlorohexadienone on the electrode surface and causing a significant decrease in the photocurrent. The developed biosensor could detect miRNA-396a at concentrations from 0.5 fM to 5000 fM, with a detection limit of 0.13 fM. Further, the proposed method can also be used to investigate the effect of heavy metal ions on the expression level of miRNAs. Results suggest that the biosensor developed herein offers a promising platform for the ultrasensitive detection of miRNA.
关键词： S9.6 antibody,Histostar@AuNPs,MicroRNA detection,MoS2/g-C3N4/black TiO2 heterojunction,Photoelectrochemical biosensor
更新于2025-11-14 17:04:02
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NiSe as an effective co-catalyst coupled with TiO2 for enhanced photocatalytic hydrogen evolution
摘要： Construction of semiconductor heterojunctions can effectively accelerate the separation of photo-induced charge carriers and thereby enhance photocatalytic activity. Here, NiSe was used as an effective co-catalyst to construct an active NiSe/TiO2 heterojunction for improving the photocatalytic H2 production of TiO2. The resultant 10%NiSe/TiO2 heterojunction exhibited 11 times higher photocatalytic H2-production activity than that of bare TiO2. The NiSe/TiO2 heterojunction and the photo-reduction of partial Ni2t to Ni0 notably accelerated the separation and transfer of photo-excited electron-hole pairs, and thus resulted in obvious improvement of H2-evolution activity. This work holds promise for the application of NiSe in photocatalysis as a high-efficiency photocatalytic cocatalyst.
关键词： NiSe/TiO2,Photoreduction,Heterojunction,Metal Ni0,Photocatalytic H2 evolution
更新于2025-11-14 17:04:02