Dye-sensitized Solar Cells Research Articles

Fifty Shades of Phenanthroline: Synthesis Strategies to Functionalize 1,10-Phenanthroline in All Positions.

1,10-Phenanthroline (phen) is one of the most popular ligands ever used in coordination chemistry due to its strong affinity for a wide range of metals with various oxidation states. Its polyaromatic structure provides robustness and rigidity, leading to intriguing features in numerous fields (luminescent coordination scaffolds, catalysis, supramolecular chemistry, sensors, theranostics, etc.). Importantly, phen offers eight distinct positions for functional groups to be attached, showcasing remarkable versatility for such a simple ligand. As a result, phen has become a landmark molecule for coordination chemists, serving as a must-use ligand and a versatile platform for designing polyfunctional arrays. The extensive use of substituted phenanthroline ligands with different metal ions has resulted in a diverse array of complexes tailored for numerous applications. For instance, these complexes have been utilized as sensitizers in dye-sensitized solar cells, as luminescent probes modified with antibodies for biomaterials, and in the creation of elegant supramolecular architectures like rotaxanes and catenanes, exemplified by Sauvage's Nobel Prize-winning work in 2016. In summary, phen has found applications in almost every facet of chemistry. An intriguing aspect of phen is the specific reactivity of each pair of carbon atoms ([2,9], [3,8], [4,7], and [5,6]), enabling the functionalization of each pair with different groups and leading to polyfunctional arrays. Furthermore, it is possible to differentiate each position in these pairs, resulting in non-symmetrical systems with tremendous versatility. In this Review, the authors aim to compile and categorize existing synthetic strategies for the stepwise polyfunctionalization of phen in various positions. This comprehensive toolbox will aid coordination chemists in designing virtually any polyfunctional ligand. The survey will encompass seminal work from the 1950s to the present day. The scope of the Review will be limited to 1,10-phenanthroline, excluding ligands with more intracyclic heteroatoms or fused aromatic cycles. Overall, the primary goal of this Review is to highlight both old and recent synthetic strategies that find applicability in the mentioned applications. By doing so, the authors hope to establish a first reference for phenanthroline synthesis, covering all possible positions on the backbone, and hope to inspire all concerned chemists to devise new strategies that have not yet been explored.

Enhancing dye-sensitized solar cell performance: Optimizing Cu2ZnSnS4/ZnCo2O4 nanocomposites as efficient and cost-effective counter electrodes

This study investigates the utilization of Cu2ZnSnS4/ZnCo2O4 (CZTS/ZCO) nanocomposites prepared through hydrothermal and combustion methods as counter electrodes in Dye-Sensitized Solar Cells (DSSCs). Different ratios of Cu2ZnSnS4 and ZnCo2O4 were explored, and comprehensive analyses were conducted using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), High-Resolution TEM (HRTEM), Brunauer–Emmett–Teller (BET) surface area analysis, Raman Spectroscopy, Electrochemical Impedance Spectroscopy (EIS), cyclic voltammetry (CV), Tafel analysis, Field Emission Scanning Electron Microscopy (FESEM), and Incident Photon-to-Electron Conversion Efficiency (IPCE), alongside long-term stability assessments. The CZTS:ZCO ratio of 2:1 exhibited the highest efficiency, reaching 8.81 %, with an open-circuit voltage of 729 mV, short-circuit current of 17.80 mAcm−2, and a fill factor of 67.9 %. This surpasses the efficiency of the reference Pt cell (8.42 %), which had an open-circuit voltage of 735 mV, short-circuit current of 17.16 mAcm−2, and a fill factor of 66.8 %. The average crystallite sizes for the main peaks of CZTS and ZCO samples were estimated to be 19.8 and 16.7 nm, respectively. The crystallite size can significantly affect the charge transfer and conductivity in the counter electrode during electrochemical processes; the presence of nanocrystals with these sizes can notably enhance the electrochemical properties and conductivity of the synthesized samples. Raman analysis results indicate that no additional phases or secondary phases such as ZnS and CuSnS3 have formed in the kesterite CZTS structure, and the crystal has formed as a single phase. Additionally, the F2g modes in the Raman spectrum of ZCO indicate tetrahedral units in the spinel ZCO structure, and the A1g modes represent octahedral structures in this phase, indicating the formation of suitable ZCO phase. The superior performance of the CZTS/ZCO nanocomposite can be attributed to its enhanced crystalline structure, superior charge transport characteristics, and improved electrocatalytic behaviours.

Photoinduced Charge Transport Dynamics under the Influence of an Electric Field on Dye-Sensitized Solar Cells with a D−π–A Structure

Photoinduced Charge Transport Dynamics under the Influence of an Electric Field on Dye-Sensitized Solar Cells with a D−π–A Structure

Design of highly efficient 0D/1D TiO2 photoanode for dye-sensitized solar cells by simple TiCl4 pre-treatment of titanate nanotubes

Dye-sensitized solar cells (DSCs) represent a promising avenue for sustainable energy conversion, with the efficiency of these devices heavily reliant on the performance of the TiO2 photoanode. Despite significant advancements, optimizing the photoanode material for higher efficiency remains a challenge. This study introduces a novel approach to constructing a highly efficient, multifunctional 0D/1D TiO2 composite by simply pre-treating the TiO2 precursor, specifically one-dimensional (1D) H-titanate nanotubes, with TiCl4. The TiCl4 treatment not only encourages the extensive synthesis of the one-dimensional nanostructures (i.e., nanorods) but also facilitates the in situ hydrolysis to generate small crystals that attach to the surface of the nanorods. The TiO2 composite offers several essential benefits, including the expanded thickness, high surface area for superior dye adsorption, efficient diffuse light scattering induced by the aggregate structures, and fast charge transport within the film matrix, making it an exemplary component for DSCs. The photovoltaic performance test revealed that TiCl4 pre-treatment increased power conversion efficiency by 36.3 %, rising from 7.63 % of untreated cells to a striking value of 10.4 %, which is a new record when N719 is used as a sensitizer and iodide-based redox shuttle employed as an electrolyte. This research provides an effective strategy for developing highly efficient photoanode material for DSCs.

Thymus schimperi Ronniger plant flowers extracted dye-sensitized solar cells

Abstract Today’s energy demand is highly increased with the world’s population growth and technological advancement. Natural dye-sensitized solar cells (N-DSSCs) are attracting research areas as an alternative and renewable energy source due to their simple preparation technique, availability, cost-effectiveness, and environmentally friendliness. In the present work, we have successfully fabricated DSSC from Thymus schimperi Ronniger plant flowers for the first time. The solvents used for extraction of the flower dye were deionized water and its mixture with ethanol. The Thymus schimperi Ronniger flowers extracted dye solutions and sensitized photoanodes were characterized by FTIR and UV-Vis characterization techniques. The crystallinity of TiO2 film was analyzed by the XRD technique and shows pure anatase phase behavior. The photoelectrochemical solar cell performance parameters, like, short circuit current density (JSC), open circuit voltage VOC), fill factor (FF), and efficiency were evaluated from the current density-voltage (J-V) measurement using a Keithley 2450 source meter. DSSC sensitized with extracted dye solution by the mixture of water and ethanol showed better performance (1.37%) as compared with that of extracted dye solution by Deionized water alone (1,02%). 

Keywords: Renewable energy, Dye-sensitized solar cells, Thymus Schimperi Ronniger, photoelectrochemical

Impact of blocking layers based on TiO2 and ZnO prepared via direct current reactive magnetron sputtering on DSSC solar cells

The optimization of dye-sensitized solar cells (DSSCs) technology towards suppressing charge recombination between the contact and the electron transport layer is a key factor in achieving high conversion efficiency and the successful commercialization of this type of product. An important aspect of the DSSC structure is the front blocking layer (BL): optimizing this component may increase the efficiency of photoelectron transfer from the dye to the semiconductor by reduction charge recombination at the TiO2/electrolyte and FTO/electrolyte interfaces. In this paper, a series of blocking layer variants, based on TiO2 and ZnO:TiO2, were obtained using the reactive magnetron sputtering method. Material composition, structure and layer thickness were referred to each process parameters. Complete DSSCs with structure FTO/BL/m-TiO2@N719/ EL-HSE/Pt/FTO were obtained on such bases. In the final results, verification of opto-electrical parameters of these cells were tested and used for the conclusions on the optimal blocking layer composition. As the conclusion, application of blocking layer consists of neat TiO2 resulted in improvement of device efficiency. It should be noted that for TiO2:ZnO/CuxO and TiO2/CuxO cells, higher efficiencies were also achieved when pure TiO2 was used as window layer. Additionally it was proven that the admixture of ZnO phase inspires Voc and FF growth, but is overall unfavorable compared to pristine TiO2 blocking layer and the reference cell, according to the final cell efficiency.

A DFT and TD-DFT studies of the photosensitizing capabilities of thiophene-based dyes

Dye-sensitized solar cells (DSSCs) play a significant role in the development of affordable, safe, and efficient solar energy technology. In this research, we have designed nine new dyes (J01-09) by modifying an experimentally reported thiophene-based dye (DSS) in the literature. The diethylaniline in the DSS as the electron donating group was replaced with diphenylamine to reduce planarity in the dye. The designed dyes all have donor and acceptor groups linked by a π-linker group (D-π-A). Using DFT and TD-DFT, we investigated the impact of the diphenylamine moieties on the planarity, photochemical and photophysical properties of the modeled dyes in isolation. The optimized structures, UV–Vis absorption, photochemical, and photovoltaic parameters were computed to study the photosensitizing capability of the modeled dyes. The photochemical and photovoltaic parameters of the study include; open-circuit voltage (VOC), light-harvesting efficiency (LHE), driving force of electron injection (ΔGinj), driving force of regeneration (ΔGreg), excited-state lifetime (τ), ionization potential (IP), adiabatic ionization potential (AIP), vertical ionization potential (VIP), electron affinity (EA), chemical hardness (η), electrophilicity index (ω), electron-donating power (ω-) and electron-accepting power (ω+) were calculated. Our findings indicate that only J03 and J08 absorb at longer wavelengths (719 and 753 nm respectively) indicating lower absorption energy bandgap compared to the DSS dye, attributed to the extension of conjugation between the thiophene and donor groups. Also, only J03 and J08 exhibited lower ΔGinj values (−0.985 and −0.667 eV respectively) and ΔGreg values (0.245 and 0.179 eV respectively) implying the dyes can be regenerated spontaneously compared to the DSS dye. Therefore, J03 and J08 are more promising to be developed as a superior photosensitizer in DSSCs.

A review of the emerging technologies in solar cells: Dye-sensitized solar cells and quantum dot-sensitized solar cells

In the current energy crisis, more efficient and clean energy sources are needed to help move the primary energy source away from fossil fuels. Fossil fuels are one of the main contributors to greenhouse gas emissions and are shown to be unsustainable. Efforts have been made in many fields surrounding renewable energy sources, with wind power, hydropower, and nuclear power being the well-known ones. Solar power is another field that has shown tremendous promise in being a clean, renewable energy source. Dye-sensitized solar cells(DSSCs) and quantum dot-sensitized solar cells(QDSSCs) have significantly advanced over the past 30 years. They are showing great potential as the production cost for DSSCs drops and the efficiency of QDSSCs rises with every passing year. This article shows the primary working mechanism of the two solar cells, compares them, and discusses their prospect of them.

Colour gamut analysis of low‐cost dye‐sensitised solar cells using natural dyes

AbstractDue to the increasing effects of greenhouse gases and environmental pollution, the need for new clean energies like solar energy attracts much attention. Although the characteristics and the efficiency of green photovoltaic devices have been researched, the colour gamut achievable from those devices has not been studied. This study investigates the colour gamut of low‐cost dye‐sensitised solar cells (DSSCs). To do this, 14 natural dye extracts were obtained from herbal resources including dragon fruit, blueberry, mango, radish, yellow rose, red cabbage, sour pomegranate, beetroot, olive, green cabbage pepper, eggplant, parsley, bramble and cherry, and employed as photosensitiser in solar cells. Then, the colorimetric attributes of the photosensitisers were studied in three‐dimensional (3D)‐colour space, that is, CIELab, CIELCH and CIE1931 chromaticity diagram. Additionally, the convex hull method was employed to determine the colour gamut boundary and the corresponding colour gamut volume. Results showed that the majority of samples benefited from approximately 3°–82° of hue angle in a*b* diagram of CIELab colour space and showed the yellowish to reddish tint effects. In CIELCH colour order system, cherry and parsley showed the lowest and highest lightness attributes while the chroma property of samples varied from minimum 1.2 for eggplant to maximum 60.2 for the dragon fruit. Moreover, the results of using the convex hull method showed the volume of 7.73 × 104 that is bounded by the colour gamut of 3D colour points over the CIELab colour space.

Effect of Natural Dye Extracts on the Absorbance Characteristics of TiO2 in Dye-Sensitized Solar Cells

Natural dye extracts from Chinese Ixora (Ixora chinensis) flower, Cassod flower (Cassia Siamea), Cassava leaf (Manihot Esculenta), purple heart (Tradescantia Pallida) and Copper leaf (Acalypha Wilkesiana) have been explored as sensitizers for the fabrication of dye-sensitized solar cells. The properties of the dyes were investigated using the FTIR and they all showed broad absorption bands in the 3800 to 3000cm-1 wavelenght and strong presence of intermolecular H-bonds. The effect of dye extracts on the absorbance and transmittance features of TiO2 was well studied by the UV-VIS and the absorbance peak was in the case of sensitization with Manihot Esculenta seen to radically improve above 1.0 at 350nm wavelength. Finally, the current and voltage characteristics of the DSSC were studied in sunlight and at a peak sunlight intensity of 601m/w2, the Manihot and Cassod sensitized devices exhibited maximum voltage values of 115 and 84mV respectively and maximum current values of 4.32 and 2.99mA. These plants have shown great potential for application in fabrication of cost effective and environmentally friendly DSSCs.

How Components of Dye-sensitized Solar Cells Contribute to Efficient Solar Energy Capture

Herein, we reviewed the main components of dye-sensitized solar cells (DSSCs) which are an emerging cheap and environmentally benign alternative for solar energy capture and conversion to electricity. The role of individual parts such as the semiconductor electrode, counter electrode, photosensitizer, electrolyte, and substrate and their contribution to the overall efficiency (η) of DSSCs are discussed. In addition, parameters such as short circuit current, open circuit voltage, and fill factor used to quantify the efficiency of DSSCs are addressed. The highest solar-to-electric energy conversion efficiency of 13 % has been achieved using titanium dioxide as a semiconductor electrode, a triiodide system as a redox couple, and platinum counter electrodes. Semiconductors are made up of materials such as glass, carbon, conductive polymers and other metal oxides have lower efficiencies (< 8 %). In addition, synthetic photosensitizers especially ruthenium complexes have higher efficiencies (10-11 %) compared to natural dyes among which the highest efficiency (4.6 %) was achieved using chlorophyll. The performance of natural dyes based on efficiency of the DSSC is generally in the order: chlorophyll > anthocyanins > carotenoids that is highly attributed to their structure which not only dictates electron release and recombination but also attachment to other components. The DSSC performance is not fixed but rather tunable by variations in the components to achieve desired structural and electronic properties such as firm anchorage between the photosensitizer and the semiconductors, the reduction of the energy band gap by incorporation of other metal salts to extend the absorption range and use of additives that prevent electron recombination with the photosensitizer or any hindrances in the electrolyte redox reactions.

Synergistic effects of polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) blends in gel electrolytes for efficient and long-term stability in dye-sensitized solar cells (DSSCs)

In this work, the stability issues associated with liquid electrolyte-based dye-sensitized solar cells (DSSC) have been addressed by introducing polymer gel electrolytes. The synergistic combination of polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) has been achieved through solution blending. Ionic conductivity measurements, scanning electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy have been employed for analysis. Optimal cohesiveness was observed at PVP concentrations exceeding 40 %, with the best outcomes achieved at a 50 % PVDF-PVP weight ratio. The electrolyte solution, comprising the polymer blend, suitable solvents, and iodine-based salts, exhibits peak conductivity (2.33 mScm⁻1) at a 10 % salt content. DSSCs utilizing the PVDF & PVP polymer blend gel electrolytes demonstrate enhanced durability and maintained efficiency at 5.43 %, exhibiting only a modest 12 % reduction compared to liquid electrolyte counterparts. Over two weeks, the fabricated DSSCs exhibited consistent photovoltaic performance, while conventional cells experienced significant declines in short-circuit current (36 %) and open-circuit voltage (33.33 %). This study signifies a promising advancement in solar cell technology, showcasing improved stability and performance in DSSCs using conductive polymer blend gel electrolytes.

Competition between Transport and Recombination in Dye Solar Cells at Low Light Intensity

The efficiency of electron collection in a dye‐sensitized solar cell (DSC) is determined by a delicate balance between electronic transport and recombination losses caused by electron transfer to dye cations and electron acceptors. While state‐of‐the‐art DSCs have demonstrated quantitative electron collection under standard 1 sun conditions, the nonlinear nature of the trapping/detrapping dynamics in the photoanode with respect to the stored electronic charge can result in suboptimal performance under the low illumination intensity conditions commonly found indoors. Herein, the key factors influencing electron collection in relation to light intensity using impedance spectroscopy and numerical analysis are thoroughly examined. Impedance analysis reveals that the electron diffusion length tends to decrease as the quasi‐Fermi level is lowered, approaching the critical limit (Ln/d ≈ 1) at intensities characteristic of indoor illumination. A range of tert‐butyl pyridine concentrations and different thermal and chemical treatments of the TiO2 are tested, showing that this low intensity limitation is inherent to the multiple‐trapping mechanism that governs the functioning of a DSC. It is concluded that relatively high ideality factors, nonoptimal electrolyte compositions, or small variations in the quality of the TiO2 layer can result in electron collection limitations that are not apparent under 1 sun but become noticeable at low light intensities.

Optimization of electrolyte co-additives, TiO2 thickness, and dye concentration for the enhanced performance of dye-sensitized solar cells

Optimization of electrolyte co-additives, TiO2 thickness, and dye concentration for the enhanced performance of dye-sensitized solar cells

Consistent behaviors of KI in heat, light and electric fields towards the inversely vulcanized dicyclopentadiene cathode for lithium-sulfur batteries

The sulfured dicyclopentadiene (S-DCPD) is a promising cathode candidate for Li-S batteries. Enlightened by the function of KI in dye-sensitized solar cells, we employ KI as a catalyst in the preparation of S-DCPD without eliminating it in the assembly of Li-S batteries. As a result, the sulfurizing reaction proceeds more completely at a lower temperature. The as-prepared material exhibits a different light response to the blank sample, changing from a higher energy level to a lower one. And the electrochemistry is greatly elevated as well. Theoretical calculations validate that KI plays the key role by altering the electron transmitting path. We can thus unify the behaviors of KI in the field of heat, light, and electricity, phenomenally. Furthermore, we investigate the morphology changes of the electrode by dipping it in an ordinary solution and subjecting it to a cycle calendar life in the electrolyte, respectively. As a result, we make clear that the difference of the behaviors between ordinary solutions and electrolytes is also in associated with the electronic path of KI.

In-depth investigation of microstructure and optical properties of tri-phase TiO2 nanoparticles at varied calcination temperatures for dye sensitized solar cells (DSSCs) applications

Tri-phase TiO2 nanoparticles are synthesized by facile hydrothermal method and calcinated within a temperature range of 450 °C–1050 °C. These nanoparticles are utilized as photoanode material in dye-sensitized solar cell (DSSC) applications. The device fabricated by utilizing TiO2 NPs calcinated at 600 °C reveals a maximum power conversion efficiency (η) of 3.79 %, with a current density (Jsc) of 7.83 mA cm−2 under one sun illumination among all tested devices. This exceptional achievement is related to the synergistic effect of 49 wt % anatase, 39 wt % rutile and 12 wt % brookite content in triphasic TiO2 NPs. The anatase emerges as the most active phase providing a sufficient surface area for dye adsorption, and in parallel rutile phase enhances the scattering of light that potentially boosts mobility and injection of photogenerated electrons (e-s) from the LUMO level (ELUMO = −3.8 eV) of N719 dye to the conduction band (ECB = −4.28 eV). Simultaneously, the presence of the brookite phase reduces the charge-carriers ((e−), (h+)) recombination rate at the TiO2 photoelectrode/electrolyte interfaces because brookite has an inherent resistance to back electron transfer. The effective light-harvesting capabilities of triphasic TiO2 NPs position them as promising contenders for dye-sensitized solar cells (DSSCs).

Nano tumbleweed-like tungsten disulfide as a viable surrogate for platinum counter electrodes in dye-sensitized solar cells

Tungsten disulfide (WS2), a notable member of the transition metal dichalcogenides family, has emerged as a promising candidate for energy storage and conversion applications. In this study, WS2 was synthesized via a hydrothermal method using sodium tungstate and thiourea as precursor materials, with hydroxylamine hydrochloride as the reducing agent and cetyl trimethyl ammonium bromide as a surfactant. The primary objective was to develop a cost-effective, easily synthesized, and scalable material capable of replacing platinum (Pt) in dye-sensitized solar cells (DSSCs), where Pt is both prohibitively expensive and scarce. Characterization of the synthesized WS2 was conducted through a range of physical analyses, including SEM, TEM, XRD, EDAX, FTIR, and Raman spectroscopy, which provided compelling evidence for the formation of a unique nano-tumbleweed-like structure of WS2. When used as a counter electrode (CE), the synthesized WS2 exhibited exceptional photocatalytic activity, resulting in a commendable power conversion efficiency (PCE) of 12.06 % when coupled with fluorine-doped tin oxide (FTO) plates coated with TiO2 as the photoanode, N719 as the dye, and Iˉ/I3ˉ as the liquid electrolyte. Additionally, the fabricated device underwent comprehensive electrical characterization, including cyclic voltammetry (CV), current-voltage (IV) measurements, electrochemical impedance spectroscopy (EIS), and Tafel analysis, revealing properties similar to those of Pt counter electrodes. Notably, WS2 demonstrated an open-circuit potential of 852 mV and a short-circuit current density of 28 mA/cm2, accompanied by a fill factor of 0.43 and a commendable lifetime of 15.92 ms.

Interfacial Mass Diagnostics: Quantitative Perspective on Construction and Mechanism Understanding of Dye-Sensitized, Perovskite and Quantum Dots Solar Cells.

Dye-sensitized solar cells (DSSCs), quantum dot-sensitized solar cells (QDSSCs) and perovskite solar cells (PSCs) have attracted wide attention. DSSCs, QDSSCs and PSCs can be prepared by liquid phase or solid phase, which causes a certain range of interface micro-mass changes during preparation. In addition, the photoelectric conversion process occurring inside the device also inevitably causes interface micro-mass changes. Interpretation of these interface micro-mass changes can help to optimize the cell structure, improve the stability and performance repeatability of the device, as well as directly or indirectly infer, track and predict the internal photoelectric conversion mechanism of the device. Quartz crystal microbalance (QCM) is a powerful tool for studying surface mass changes, extending this technology to the fields of solar cells to directly obtain interface micro mass changes, which makes the research more in-depth and opens up a new perspective for explaining the basic principles of solar cells. This review summarizes the research progress of QCM application in DSSCs, QDSSCs and PSCs in recent years, and explores the challenges and new opportunities of QCM application in new solar cells in the future.

Electrical energy efficiency of dye sensitized solar cells by polymer electrolyte

This research aims to prepare by mixtures method with dope carbon black as a working electrode and the apply it to the dye sensitized solar cells (DSSCs). The thin film of titanium dioxide nanocrystalline semi - conductor with dope carbon black, the cells were coated on to transparent conducting oxide glass sheet by means of the doctor blade technique as a working electrode. But the polymer electrolyte were prepare by adding potassium iodide and iodine salts with a ratio of KI:I2 was 10:1, into a polymer electrolyte composed of poly-ethylene glycol, ethylene carbonate and poly(styrene–co–acrylonitrile). The polymer electrolyte mixtures became homogeneous and stirring at a temperature of 80 °C. Found that efficiency for the DSSCs by polymer electrolyte based on yielded an overall light to electrical energy conversion efficiency ( ) of the DSSCs was 5.5095%, An open-circuit voltage of 0.58 V, voltage at the point of maximum power output of 0.42 V, short-circuit current density of 11.11 mA.cm–2, current density at the point of maximum power output of 10.50 mA.cm–2 fill factor of 0.684 under an irradiation of 80 mW.cm–2. And the long-term stability test of the DSSCs with a polymer electrolyte is evidently superior to the DSSCs with liquid electrolyte based on the observation period lasting for 90 days. GRAPHICAL ABSTRACT HIGHLIGHTS prepare by mixtures method with dope carbon black as a working electrode The efficiency for the DSSCs by polymer electrolyte based on yielded an overall light to electrical energy conversion

Enhanced photovoltaic performance of dye sensitized solar cells using cesium bromide modified TiO2 electron transport layer

TiO2 is one of the most widely explored materials as an electron transport layer (ETL) in dye sensitized solar cells (DSSCs) due to its excellent physical and chemical properties. However, recombination at the device's interface slackens the charge carrier movement, adversely affecting their device performance. Rapid extraction of photogenerated charge carriers plays a vital role in developing high efficiency DSSCs. The conduction band alignment of TiO2 ETL and N719 dye light absorber plays a crucial role in charge carrier dynamics of DSSCs. Herein, the band structure of TiO2 ETL is finely tuned by the incorporation of cesium bromide (CsBr). At the optimal concentration (0.4 Wt. %), DSSCs achieved the best power conversion efficiency (PCE) of 9.28 % compared to 7.61 % for pristine TiO2. The modified TiO2–CsBr ETL induced a negative shift in flat band potential (Vfb) from −0.46 to −0.50 V, which improved the open circuit voltage (VOC), its work function (ɸ) from −4.71 to −3.75 eV and increased conduction band minimum (CBM) from −3.58 to −2.42 eV. CsBr incorporation increased electron density in TiO2 matrix, indicating the suppression of trap state and significantly improved the overall photovoltaic performance of DSSCs.