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Charge transport and electron recombination suppression in dye-sensitized solar cells using graphene quantum dots
摘要： In this study, TiO2 photoelectrodes were sensitized in different concentration of Graphene Quantum Dots (GQDs) solution to enhance photovoltaic performance and charge transport of DSSC. The performance of pristine TiO2 and TiO2-GQDs photoelectrodes were compared to investigate the effect of GQDs incorporation in DSSC. It was found GQDs increased light absorption of TiO2 photoelectrode at visible spectrum in the range of λ = 375 nm to λ = 600 nm, resulting highest current–density, Jsc and photon-to-current conversion efficiency, ?c. Solar cell sensitized in 7.5 mg/ml concentration of GQDs known as (PG 7.5) cell shown the highest reading by 15.49 mA cm?2 and 6.97%, which indicated an improvement by 28.07% and 70.83% for Jsc and ? compare to pristine TiO2 DSSC at 12.10 mA cm?2 and 4.08%. Photoluminescence property own by GQDs may enhance photon emission to visible region when uv-ray excited on solar cell. Thus, generate more electron-hole pairs in the photoelectrode and enhance the photovoltaic parameters of DSSC. PG 7.5 cell also exhibited lowest series resistance (Rs) of 36.60 Ω, highest charge transfer resistance (Rct2) of 41.98 Ω and electron lifetime of 6.33 ms among other DSSC. These possibly due to suppression of recombination between TiO2/dye/electrolyte interfaces. Hence, resulting highest charge collection efficiency (CCE) of 53.42%. The EIS analysis confirmed the PV performance of the best cell of PG 7.5 since the same cell also generated the best photon-current conversion efficiency (PCE). This study revealed GQDs can enhanced photovoltaic parameter and charge collection efficiency of DSSC.
关键词： Charge collection efficiency,GQDs-DSSC,TiO2-GQDs,Charge transport
更新于2025-11-14 17:04:02
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Synthesis, characterization and dye sensitized solar cell application of Zinc oxide based coaxial core-shell hetrostructure.
摘要： In the present work, the ZnO/CdS coaxial core shell hetrostructure has been synthesized on indium doped tin oxide glass substrate using chemical solution methods and further it is used as photoanode in the DSSC application. Four samples with different concentration of sulphur source were prepared. An approximate crystallite size of 22 nm for ZnO and 18 nm for CdS has been obtained as analyzed from X-ray diffraction data. FESEM and HRTEM images confirm the formation of CdS shell on ZnO nanorods with a width below 100 nanometer. UV-visible spectroscopy and photoluminescence spectroscopy were used to examine the optical response revealing the fact that band gap reduction and a small red shift takes place for core shell structure as compared to bare ZnO nanorods array. The J-V characterization was performed to study the photovoltaic response. An improved efficiency was observed for core shell ZnO/CdS hetrostructure (3.66%) as compared to bare ZnO nanorods based DSSCs (0.70%). This improvement is due to increased current density caused by reduced recombination of photogenerated electron hole pairs. This reduced recombination is achieved by two factors, one is formation of type two core shell hetrostructure and second is increasing sulphur concentration in shell structure.
关键词： DSSC,Hetrostructure,FESEM,HR-TEM,coaxial core-shell
更新于2025-11-14 17:04:02
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Investigation of semi- transparent dye-sensitized solar cells for fenestration integration
摘要： For any particular location glazing transmission varies with season and time of day. Thus, glazing transmission angular behaviour is more crucial than single glazing transmittance value for building energy simulation and design. In this work, the spectral behaviour of the dye-sensitized solar cell (DSSC) glazing with three different transparencies are studied. Transmittance of the devices are measured after 2 years to understand the effects of device stability on DSSC glazing applications. The solar factor for the devices is calculated for different light incident angles for a whole year at a particular location. The correlation between clearness index and DSSC transmittance is also studied. Finally, glare analysis is performed for all the devices on a sunny day, intermittent day and overcast day, and is also compared with double glazing. It is found that the 37% transparent DSSC glazing leads to a greater reduction in disturbing glare by 21% compared to double glazing on a clear sunny day. All the above results suggest that DSSC glazings could be productively used for fenestration integration in buildings.
关键词： DSSC,clearness index,daylight glare,glazing,solar factor,angular transmission
更新于2025-10-22 19:40:53
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Theory for IMPS on Rough and Finite Fractal Dye Sensitized Solar?Cell
摘要： A generalized theoretical model of intensity modulated photocurrent spectroscopy (IMPS) for the random morphology in a dye sensitized solar cell (DSSC) under uniform illumination is developed. The generalized IMPS expression for the disordered semiconducting/conducting glass interface of a DSSC is obtained in term of power spectral density of roughness. Influence of surface roughness on the dynamic response of DSSC originate due to the coupling of characteristic phenomenological and morphological length scales. A detailed analysis of IMPS response is performed over finite self-affine fractals to highlight roughness induced anomalies and cause of photocurrent enhancement. The IMPS of a rough DSSC exhibit three characteristic frequency regimes: lifetime of charge carrier dependent low frequency regime, surface irregularity dependent intermediate power-law regime and diffusion controlled high frequency regime. Finally, our theory facilitates the understanding of dynamics and kinetics of charge carriers under the influence of ubiquitous surface disorder.
关键词： DSSC,charge transport,fractal,surface roughness,IMPS
更新于2025-09-23 15:23:52
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Theoretical study of the effects of modifying the structures of organic dyes based on N,N-alkylamine on their efficiencies as DSSC sensitizers
摘要： In this work, we carried out a theoretical study in which DFT and TD-DFT calculations of a series of six new organic dyes that incorporate N,N-alkylamine as an electron donor and a cyanoacrylic acid group as an electron acceptor and anchoring group were performed. In each dye, the donor and the acceptor were bridged by six different π-conjugated spacers consisting of an auxiliary donor group (3,4-ethylenedioxythiophene, EDOT) or an auxiliary acceptor group (benzothiadiazole, BTZ or diketopyrrolopyrrole, DPP) that was linked to either thiophene or phenyl. EHOMO, ELUMO, Egap, λmax, Eex, the open-circuit photovoltage (Voc), the light-harvesting efficiency (LHE), and the free injection energy (ΔGinject) were calculated for all of the dyes to compare their photovoltaic performance. The effects of the incorporation of an additional acceptor group (DPP or BTZ) or an additional donor group (EDOT) into the π-bridge on the geometry, electronic structure, and photovoltaic performance of each designed dye were explored. The study shows that modifying the dye skeleton can greatly improve the performance of the dye and increase its power conversion efficiency. It also reveals that all of the studied dyes are promising candidates for an effective DSSC sensitizer, especially those that include the acceptor group DPP in the π-bridge.
关键词： DSSC,BTZ,N,N-alkylamine,DPP,EDOT
更新于2025-09-23 15:22:29
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Synthesis, characterization of TiO <sub/>2</sub> nano particles for enhancement of electron transport application in DSSC with Cu-BPCA Dye
摘要： Dye-sensitized solar cells [DSSCs] have attracted extensive attention due to their potential low cost and high energy efficiency, rendering them one of the most promising system for solar-to-energy conversion. The DSSC efficiency was enhanced by intermixing with the use of TiO2 nanoparticles which provides high surface area for accommodating the light-absorbing sensitizer and also the stable conductor for photo generated electrons. In hydrothermal method, the TiO2 nanoparticles synthesis depends on temperature. TiO2 nano particles diameter depends on different autoclaving temperature.TiO2 nanoparticles have been coated on ITO glasses by screen printing method. In this work, we have synthesized TiO2 nano particles which can provide a fast way for electron transport and reduced trapping of photo injected electrons during the path of back contact. The DSSCs were fabricated using the ruthenium dye and electrolyte (I3/I3-). The crystalline structure of TiO2 has been characterized by DLS, X-ray diffraction, SEM and TEM. The absorption spectra measured by using UV-Vis spectrometer. The IR spectrum has been recorded to know the peaks of Ti-O-Ti in powder sample. It has been found that the efficiency of DSSC was highly affected by the properties of nano particles.
关键词： Nanoparticles,Dye,DSSC,Titanium Dioxide (TiO2)
更新于2025-09-23 15:22:29
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Exploring the potential of iron to replace ruthenium in photosensitizers: a computational study
摘要： In an effort to replace the widely used ruthenium metal complexes with low-cost, earth abundant iron complexes as photosensitizers for dye-sensitized solar cell (DSSC) applications, herein we report the computational design of heteroleptic iron complexes (FC1–3) coordinated with benzimidazole-phenylcarbene (C^N) ligands. DFT and TDDFT calculations predicted the stronger σ-donating and π-accepting nature of phenyl carbene ligands substituted with electron-withdrawing CF3, donating –N(CH3)2, and benzothiazine annulation than the imidazole carbene ligands (FC4); consequently, the metal-ligand bond distances and interactions that influence the ordering of charge transfer states with respect to metal centered states are altered in FC1–3 complexes. Detailed analysis based on energy decomposition analysis, spin density distribution analysis, and ab initio ligand field theory parameters were enabled to understand the nature of heteroleptic ligand interactions with the rest of the metal complex. The results from the study shed light on the judicious choice of ligands, as the same non-innocent ligand that is experimentally proven as favorable for Ru-dyes (TC1) is found to be detrimental for Fe-dyes (FC1). Among the complexes studied, the FC3 complex is a promising sensitizer for DSSC with 1,3MLCT energy level well separated from 3,5MC, thereby preventing the deactivation of MLCT. The outcome of the study is therefore an important step toward the development of photosensitizers based on iron metal.
关键词： DSSC,Photosensitizers,Iron,Spin states,TD-DFT,Carbene ligands,Ruthenium
更新于2025-09-23 15:21:21
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A computational study on boron dipyromethene ancillary acceptor-based dyes for dye-sensitized solar cells
摘要： A series of (D-π)2-An-A based organic dyes containing boron dipyrromethene (BODIPY) moiety as an ancillary acceptor (An) derivative were chosen, and the effect of donor moieties (diarylamine, carbazole, azepine, and dibenzazepine) was investigated to understand their photophysical and photoelectrochemical properties by employing density functional theory (DFT) and time-dependent DFT. It is experimentally proved that BODIPY enhances the light-harvesting in red and near IR region of visible light. The electron density distribution analysis was performed for all the dyes to confirm the intramolecular charge transfer, envisioned from the simulated absorption spectra of the dyes. Carbazole donor-based dye exhibited the lowest reorganization energy. A dye attached to the TiO2 (1 0 1) surface was modeled to estimate the adsorption energy of the dyes. The density of states analysis revealed that the absence of defect states in the bandgap of TiO2 facilitates the smooth electron transfer from the excited state of the dye to the conduction band of TiO2. Considering the lowest unoccupied molecular orbital (LUMO) energy level of dyes and conduction band energy level of TiO2, it is understood that all the dyes studied in this study are capable of electron injection upon photoexcitation. Considering the driving force for dye regeneration of the dyes and the magnitude of reorganization energy, carbazole donor-based dye (D2) would be the best performing dye in DSSC. Previously, the power conversion efficiencies of the dyes have been reported, and carbazole donor-based dye (D2) exhibited the highest efficiency among all the dyes. Our computational investigations are in good agreement with the experimental results.
关键词： TiO2 (1 0 1) surface,Reorganization energy,DSSC,Dye regeneration,BODIPY
更新于2025-09-23 15:21:01
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Design, Synthesis and Photophysical Analysis of New Unsymmetrical Carbazole-Based Dyes for Dye-Sensitized Solar Cells
摘要： The molecular design, synthesis, and characterization of di-anchoring carbazole-based dyes (Car-Cy, Car-Amin, and Car-Mal) with A-π-D-π-A-π-A structure as materials for dye-sensitized solar cells applications (DSSCs) are reported. The electron-rich carbazole moiety in the structure of synthesized dyes is connected with acceptor/ or anchoring groups (cyanoacetic acid, 4-aminobenzoic acid, and malonic acid) and π-spacers (vinylene and cynovinyl thiophene). Electronic characteristics and molecular geometry of the sensitizers were optimized using Density Functional Theory (DFT), and the influence of dye structure on their photovoltaic performances was studied. Among the synthesized dyes in this research, Car-Amin dye presents a better photovoltaic performance as a sensitizer in the constructed device, with a power conversion efficiency (PCE) of 2.27%, JSC of 5.95 mAcm?2, VOC of 0.54 V and FF of 71%. The enhanced performance of this dye could be related to the powerful electron-withdrawing characteristic of the 4-aminobenzoic acid as an acceptor group in the dye structure. Consequently, the impact of various acceptor groups on the constructed DSSC devices was examined, and the results indicated that the improvement of DSSC performance is due to the presence of 4-aminobenzoic acid as acceptor on the carbazole-based dyes.
关键词： 4-aminobenzoic acid,Malonic acid,Dye-sensitized solar cell (DSSC),Carbazole,Cyanoacetic acid
更新于2025-09-23 15:21:01
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rGO based photo-anode in dye-sensitized solar cells (DSSC) and its photovoltaic characteristics
摘要： On the attempt to increase transport properties of the photo-anode in DSSC, we synthesized rGO powder from graphite bar (commercially available) using modified Hummer’s method. The SEM-EDS results had confirmed the attachment of the rGO layer to the FTO substrate. For DSSC cells, we made two cells configuration, the first one was stacking layers of rGO and TiO2 resulting configuration of TiO2/rGO/ TiO2 (A2) and rGO/TiO2/rGO (A3), where rGO was deposited by spin coating and TiO2 was deposited by a screen printing technique. The second one, the rGO powder was mixed with TiO2 paste with several ratios in weight, namely TiO2:rGO 40:1 (B1), 40:2 (B2), and 40:8 (B3) and then deposited on the FTO substrate by screen printing. The reference cell was assigned as A1 (TiO2 only). From the conductivity measurement using the four-probe method, the utilization of rGO layer increased the conductivity of photo-anode layer, namely (1.37, 2.9 and 6.3)x10-2 Ω-1cm-1 for A1 to A3 and (1.5, 2.5, and 3.7)x10-2 Ω-1cm-1 for B1 to B3. From the photovoltaic measurement, we found that the efficiency of the DSSC cell firstly increased with the insertion of rGO layer, from 1.8% (A1) to 4.59% (A2), and decreased to 3.22%, as the conductivity increased in A3. While for the composite of TiO2:rGO, the efficiency of the cell reduced with the increased amount of rGO, from 3.45% (B1) to 2.9% and 1.9% for B2 and B3. We found that the reduction of photovoltaic performance was affected by two main factors, specifically, direct contact between rGO and redox species in the electrolyte, which induced recombination process, and conductivity of the photo-anode layer. To fully achieve the advantage of rGO utilization in photo-anode, once must be considered was the use of protection layer on top of the rGO layer to avoid direct contact between the rGO/electrolyte interface.
关键词： photovoltaic,rGO,efficiency,photo-anode,DSSC,conductivity
更新于2025-09-23 15:21:01