Carbon Counter Electrode Research Articles

All-Inorganic Perovskite Solar Cells with Tetrabutylammonium Acetate as the Buffer Layer between the SnO2 Electron Transport Film and CsPbI3.

All-inorganic CsPbI3 perovskites have great potential in tandem cells in combination with other photovoltaic devices. However, CsPbI3 perovskite solar cells (PSCs) still face a huge challenge, resulting in a low power conversion efficiency (PCE) relative to organic-inorganic PSCs. In this work, we introduced tetrabutylammonium acetate (TBAAc) as a buffer layer between the SnO2 electron-transport layer (ETL) and CsPbI3 all-inorganic perovskite film interface for the first time. TBAAc not only improved the conductivity of SnO2 ETL but also formed a 1D TBAPbI3 layer between the SnO2 ETL and the 3D CsPbI3 all-inorganic perovskite film, thereby enhancing the stability and passivating the surface defects of the CsPbI3 perovskite to fabricate high-efficiency carbon-counter electrode (CE)-based CsPbI3 solar cells. We fabricated carbon-CE-based hole-transporting layer ( HTL)-free PSCs with an FTO/SnO2/TBAAc/CsPbI3/C structure. The open-circuit voltage (Voc), short circuit current density (Jsc), PCE, and fill factor of the champion CsPbI3 PSCs simultaneously enhanced to 1.08 V, 17.48 mA/cm2, 12.79, and 67.8%, respectively. This PCE is currently one of the high efficiencies reported for the above planar-structured carbon-CE-based CsPbI3 PSCs to date. Moreover, the optimized device exhibits excellent stability, which retained over 83% of its initial PCE after 350 h. This work provides a facile way of simultaneous optimization of the SnO2 ETL and the CsPbI3 perovskite layer to fabricate stable and high-efficiency carbon-CE-based CsPbI3 PSCs.

A Modified Sequential Deposition Route for High-Performance Carbon-Based Perovskite Solar Cells under Atmosphere Condition.

Carbon-based hole transport material (HTM)-free perovskite solar cells have exhibited a promising commercialization prospect, attributed to their outstanding stability and low manufacturing cost. However, the serious charge recombination at the interface of the carbon counter electrode and titanium dioxide (TiO2) suppresses the improvement in the carbon-based perovskite solar cells’ performance. Here, we propose a modified sequential deposition process in air, which introduces a mixed solvent to improve the morphology of lead iodide (PbI2) film. Combined with ethanol treatment, the preferred crystallization orientation of the PbI2 film is generated. This new deposition strategy can prepare a thick and compact methylammonium lead halide (MAPbI3) film under high-humidity conditions, which acts as a natural active layer that separates the carbon counter electrode and TiO2. Meanwhile, the modified sequential deposition method provides a simple way to facilitate the conversion of the ultrathick PbI2 capping layer to MAPbI3, as the light absorption layer. By adjusting the thickness of the MAPbI3 capping layer, we achieved a power conversation efficiency (PCE) of 12.5% for the carbon-based perovskite solar cells.

Interfacial Engineering by P-Methylphenylmethylammonium Iodide for Efficient Carbon Counter Electrode (Ce)-Based 2d/3d Hybrid Perovskite Solar Cells

Interfacial Engineering by P-Methylphenylmethylammonium Iodide for Efficient Carbon Counter Electrode (Ce)-Based 2d/3d Hybrid Perovskite Solar Cells

The first and cost effective nano-biocomposite, zinc porphyrin/CuO/reduced graphene oxide, based on Calotropis procera plant for perovskite solar cell as hole-transport layer under ambient conditions

Self-assembly of reduced graphene oxide, zinc [5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin] complex and CuO nanoparticles was performed through π–π stacking and hydrogen bonding using Calotropis procera plant to have a bio-nanocomposite (ZnPor/rGO/CuO). This green organic/inorganic ternary hybrid was constructed using bottom-up approach to have multiple electron transfer and characterized by SEM, TEM, XRD, EDX, elemental analysis, UV–Vis spectroscopy, and Cyclic voltammetry (CV). The bio-nanocomposite (ZnPor/rGO/CuO) possesses suitable energy level, high hole mobility, and excellent thermal stability. The obtained bio-nanocomposite was used as inorganic hole-transporting material (HTM) in carbon-based Perovskite Solar Cells (C-PSC). 9.8 is the best powder conversion efficiency of system in comparision with Spiro-OMeTAD as a commercial HTM. Its PCE is about 59% more than of PCE of control device (HTM free). This significant increase in PCE was due to the higher hole-extraction rate at carbon counter-electrode, in the presence of bio nanocomposite as a HTM confirming by Mott–Schottky analysis and the electrical conductivity.

Interfacial engineering with NiOx nanofibers as hole transport layer for carbon-based perovskite solar cells

Although perovskite solar cells (PSCs) have made revolutionary progress in terms of power conversion efficiency (PCE), to achieve long-term stability and low-cost device manufacturing for commercialization of the devices, selection of proper hole transport layer (HTL) and affordable back contact are still crucial to realize the upscale manufacturing. However, the carbon-based perovskite still faces great challenges to further improve the device performance due to the low quality of the carbon/perovskite interface. Inorganic NiOx is a superior HTL candidate due to its favorable energy band alignment, superior chemical stability, high hole mobility, and low-cost manufacturing. To address the poor interface quality of the carbon-based PSCs, we report electrospun NiOx fibers as an effective HTL, resulting in highly efficient device performance of PCEs up to 13.73% when deployed in our carbon-based PSCs. NiOx has been introduced as an interfacial layer between the perovskite and the carbon counter electrode to study its impact on interfacial modification and device performance.

Comparative photovoltaic and impedance spectroscopic study on carbon counter electrode based CdS quantum dot sensitized solar cell using polysulfide and iodide/triiodide as redox liquid electrolytes

In this investigation we report comparative study on the quantum dot sensitized solar sells (QDSSCs) using polysulfide and iodide/triiodide as redox liquid electrolytes aimed for the improvement in performance of CdS sensitized solar cell. The CdS films were deposited upon bare FTO and nanocrystalline mesoporous TiO2 coated FTO substrates by following a successive ionic layer adsorption and reaction (SILAR) method. The films were characterized by using atomic force microscopy (AFM) measurements and UV–Visible (UV–vis) spectroscopy. Analysing the AFM images height of the nanocrystals was found to be less than 2.84 nm. The estimated size of the CdS quantum dots (QDs) obtained using the UV–vis data and hyperbolic band model (HBM) was 4.94 nm. Photovoltaic performance and impedance spectroscopic measurements were performed on these FTO/TiO2/CdS/Electrolyte/Carbon type QDSSCs under an AM1.5 illumination (100 mW.cm−2) and dark, respectively. The overall power conversion efficiency, short circuit current and the fill factor of polysulfide based device were observed higher than the iodide/triiodide based cell by 280%, 123%, and 95%, respectively. Improvement in series resistance (Rs) and shunt resistance (Rsh) values of polysulfide based device were observed by 830%, and 348%, respectively. The results achieved using low cost ploysulfide electrolyte and carbon as counter electrode are observed higher than the results of the recent attempts made by other research groups for enhancing performance of the CdS QDSSCs using platinum as counter electrode. The better performance of FTO/TiO2/CdS/Polysulfide/Carbon type QDSSC could be attributed to the higher hole-recovery rate of polysulfide leading to a lower probability for charge recombination and the higher electrocatalytic activity at the CE/electrolyte interface resulting the fast electron injection and transfer from CdS QDs into the photoanode substrate.

Graphene oxide as an effective hole transport material for low-cost carbon-based mesoscopic perovskite solar cells

Carbon-based perovskite solar cells (PSCs) are fast developing toward large-scale production. In this study, graphene oxide (GO) was applied as a hole transport material (HTM) for carbon-based mesoscopic PSCs with n-i-p structure. The GO was prepared using a simple Hummer’s method, while the carbon counter electrode was deposited using a doctor blade and heated at a temperature of 120 °C. The mesoscopic carbon-based PSCs with various GO dispersion (1.0, 1.5, and 2.0 mg.ml−1) are fabricated and characterised for optimised photovoltaic performance. Consequently, the use of GO as HTM improved the quality of perovskite film by providing perovskite crystals with larger grain size and fewer pinholes. The power conversion efficiency (PCE) of 10.01% was obtained with GO dispersion concentration of 1.0 mg.ml−1, which was significantly higher than a similar device without HTM with a PCE of 8.32%. These results show that GO effectively serves as a promising HTM. Combined with the use of carbon as a replacement for metals as a back-contact electrode, this work demonstrates that the overall material cost for perovskite solar cells could be reduced while maintaining excellent photovoltaic performance.

Enhanced charge transport in low temperature carbon-based n-i-p perovskite solar cells with NiOx-CNT hole transport material

We report oleylamine functionalized NiOx (f-NiOx) and CNT composite (f-NiOx + CNT) as hole transport material in n-i-p low-temperature processed carbon counter electrode based perovskite solar cells. Oleylamine functionalization improves the dispersibility of NiOx, but it reduces the conductivity. We demonstrate the addition of a small amount of CNT significantly enhances the conductivity and charge transport properties. The morphological and optoelectrical properties of prepared nanoparticles were evaluated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and UV–Vis spectroscopy. The results suggest suitable energy band alignment of f-NiOx+CNT hole transport material with FA0.83Cs0.17PbI2.5Br0.5 perovskite absorber layer. Better hole extraction and transport were provided by f-NiOx + CNT hole transport material, with improved conductivity of 2.73 × 10−2 S cm−1. The fabricated device exhibits 11.36% efficiency with exceptional stability for more than 720 h (retaining ~ 60% of initial efficiency) in ambient without encapsulation. Additionally, we have also demonstrated the perovskite mini-module by connecting two small area cells in series, making the active area of 4 cm2 with 6.11% efficiency.

Wide spectral response perovskite solar cells mixed with NaGdF4:Yb3+, Er3+@NaGdF4:Eu3+ core-shell rare earth nanoparticles

In this study, NaGdF4:Yb3+, Er3+@NaGdF4:Eu3+ ([email protected]) core-shell rare earth nanoparticles are prepared by a simple hydrothermal method. After testing, the emission peaks are observed at 415, 525, 540 and 660 nm with an excitation light of 980 nm due to the up-conversion luminescence from rare-earth nanoparticles. Under light excitation at 395 nm, the rare-earth nanoparticles undergo down-conversion luminescence with emission peaks at 590, 610 and 695 nm. The resulting nanoparticles are introduced into the TiO2 mesoporous layer of hole-conductor-free perovskite solar cells (PSCs) based on carbon counter electrodes to broaden the spectral response of the cells from the visible range to the near-infrared and near-ultraviolet regions, which can guarantee a high light absorption efficiency and corresponding accelerated generation of electron-hole pairs. The results suggest that the mixing of [email protected] nanoparticles into mesoporous TiO2 layer improves the power conversion efficiency of PSCs to 14.21%, which is 10.6% higher than that of the control cells, which can pave an effective way to improve the performance of PSCs with a broadened response range.

Recent Progresses in Carbon Counter Electrode Materials for Perovskite Solar Cells and Modules

AbstractThough perovskite solar cells (PSCs) or modules (PSMs) are being developed at an unprecedented speed, several obstacles remain to their commercialization. One of the difficult problems is the expensive and unstable Au and Ag counter electrode. Therefore, highly effective, stable, and low‐cost counter electrode materials should be explored. Among various counter electrode materials, carbon is one of the most promising substitutes for their rich sources, low cost, outstanding electrochemical performance, and diversified surface functions. This review summarizes recent achievements of carbon counter electrode materials, which included commercial carbon paste, carbon black, graphite, graphene, carbon nanotubes and their synthetic approaches, modifications, and structure‐function relationships. Moreover, large‐scale carbon counter electrode in PSCs or PSMs are specifically discussed. Hopefully, this recapitulative analysis will draw the attention of relevant researchers to re‐understand the importance of counter electrode and clarify what should be noticed to develop qualified counter electrode materials for PSCs or PSMs.

Enhanced properties of low-cost carbon black-graphite counter electrode in DSSC by incorporating binders

Carbon-based counter electrodes of dye-sensitized solar cells (DSSCs) such as carbon black-graphite composite (CB/Gr) have received unprecedented interest in recent years due to their ease of fabrication, good corrosion resistance, and low cost compared to platinum (Pt) electrodes. However, the poor surface adherence between the carbon counter electrodes (CE) and FTO substrate, low surface area, and poor inter-particle connection between the carbon materials have consistently become a major challenge. In order to overcome these issues, we have fabricated CB/Gr by incorporating binders of titanium (IV) isopropoxide (TTIP), and zirconium (IV) dioxide (ZrO2) as the counter electrodes for the DSSC. The performance of the CE is characterized by four-point probe conductivity measurement, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and current density voltage (J-V) characteristics. The results revealed that incorporating binders to the CB/Gr has improved the series resistance (RS) and charge transfer resistance (RCT), which enhances the short-circuit current density (JSC), fill factor (FF), and the power conversion efficiency (PCE) of the device. The TTIP binder in CB/Gr CE exhibited superior performance in DSSC is largely attributed to the formation of TiO2 in situ with small particle size of about 100 nm, leading to enhanced intimate contact between the carbon materials, high surface area, and better surface adherence between counter electrode and the FTO substrate. Our findings, thereby, offer the possibility to engineer and optimize the energy levels of CE in an effort to develop a high-performing DSSC counter electrode.

Label-free Electrochemical Impedance Spectroscopy Aptasensor for Ultrasensitive Detection of Lung Cancer Biomarker Carcinoembryonic Antigen.

In this work, an integrated electrode system consisting of a graphene working electrode, a carbon counter electrode and an Ag/AgCl reference electrode was fabricated on an FR-4 glass fiber plate by a polyethylene self-adhesive mask stencil method combined with a manual screen printing technique. The integrated graphene electrode was used as the base electrode, and AuNPs were deposited on the working electrode surface by cyclic voltammetry. Then, the carcinoembryonic antigen aptamer was immobilized using the sulfhydryl self-assembly technique. The sensor uses [Fe(CN)6]3−/4− as a redox probe for label free detection of carcinoembryonic antigen based on the impedance change caused by the difference in electron transfer rate before and after the binding of carcinoembryonic antigen aptamer and the target carcinoembryonic antigen. The results showed a good linear relationship when the CEA concentration is in the range of 0.2–15.0 ng/ml. The detection limit was calculated to be 0.085 ng/ml (S/N = 3).

Solid‐state Synthesis of Ni Decorated Needle Coke as Low‐cost Pt‐free Counter Electrode for Efficient Dye‐sensitized Solar Cells

AbstractTo seek a Pt‐free carbon material counter electrode for dye‐sensitized solar cells (DSSCs), the electrocatalytic activity of needle coke (NC) for the reduction of triiodide in DSSCs was investigated, and further improved by decorating with Ni to prepare Ni decorated needle coke (Ni‐NC) via a one‐step solid‐state synthesis method. It is found that the NC is a potential carbon counter electrode material for DSSCs due to its high‐density anisotropy with considerable conductivity. Although the decoration of Ni may sacrifice certain conductivity of NC, the electrocatalytic activity of Ni‐NC towards reduction of triiodide was better than that of NC. To obtain a balanced point of conductivity and electrocatalytic performance for Ni‐NC, the loading amount of Ni together with the solid‐state synthesis conditions were also studied. It is indicated that these parameters also have some effect on the performance of Ni‐NC. Under the optimized conditions, the DSSCs based on Ni‐NC counter electrode achieve an 77 % higher energy conversion efficiency of 4.39 % than that of NC counter electrode (2.48 %), and comparable to the value (5.34 %) obtains with Pt counter electrode. It is an efficient way to improve the performance of NC by decorating with Ni via a facile solid‐state synthesis method, and promote the application of needle coke as carbon counter electrode materials in DSSCs.

Stability, reusability, and equivalent circuit of TiO2/treated metakaolinite-based dye-sensitized solar cell: effect of illumination intensity on Voc and Isc values

In this research, treated metakaolinite (TMK) was introduced into the TiO2 photoelectrode to fabricated dye-sensitized solar cells (DSSCs). The photovoltaic cells have four main natural components, i.e., a photosensitizer (carotenoid bixin), photoelectrode (TiO2/kaolinite), electrolyte (glycerine carbonate derivative), and counter-electrode (carbon). Their stability, reusability, and equivalent circuit were studied. The presence of 5% of TMK in anatase TiO2 paste decreased the TiO2 band gap from 3.21 to 3.16 eV. The result showed that the presence of 5% of TMK in TiO2 paste was more favorable to obtain higher energy conversion efficiency. Under a light intensity of 200 W/m2, it produced an energy conversion yield of 0.086%. The combination of the electrolyte and the TMK demonstrated a synergistic effect to improve the electrical properties of the DSSC. The energy storage function worked well until the third day of analysis. The DSSC based on TiO2/TMK photoelectrode exhibited 16 times better stability than pure TiO2-based photoelectrode. The Faraday charge transfer processes showed that the TiO2/TMK photoelectrode is not in direct contact with the carbon counter-electrode.

Hyperstable Perovskite Solar Cells Without Ion Migration and Metal Diffusion Based on ZnS Segregated Cubic ZnTiO3 Electron Transport Layers

Perovskite solar cells (PSCs) have attracted great interest in recent decade, however, stability issue and large‐scale application still remain as roadblocks to their practical applications. To settle aforementioned issues, metal diffusion and ion migration should be controlled to improve long‐term operational stability. Herein, cubic zinc metatitanate (ZTO) is optimized and improved by segregating with surface sulfidation. The sulfurized electron transporting layer, label as ZTO‐ZnS, based PSCs achieved an amazing power conversion efficiency (PCE) of 21.3%. A large‐area module (8.0 cm2 active area) based on ZTO‐ZnS is also developed with 15.9% PCE. Furthermore, combining with inorganic CuI hole transporting layer and carbon counter electrode, metal diffusion, and ion migration effect are eliminated drastically in ZTO‐ZnS‐based PSCs. The combined PSC devices can easily keep more than 85% initial PCE after 1 000 h at 85 °C in air with a relative humidity of 85% under maximum power point and continuous AM 1.5G illumination. The persistence in stability is investigated and revealed fully by energy dispersive spectrometer analysis, attributing to the PSC structure which blocks the metal diffusion and ion migration in the devices. A big step forward industrialization and commercialization for PSCs is made.

Effects of Activated Carbon Counter Electrode on Bifacial Dye Sensitized Solar Cells (DSSCs)

The losses of solar cells are consisted of electrical losses and optical losses. Optical losses chiefly reduce the short-circuit current. Here we apply bifacial cell approach to increase light absorption and the short-circuit current of dye sensitized solar cells (DSSCs). We have employed activated carbon (AC) as a very low cost counter electrode, an alternative to Pt counter electrode. Addition of dimethyl sulfoxide (DMSO) and titanium carbonitride (TiCN) to AC increase the efficiency of bifacial DSSC at a mirror angle of from 5.10% to and , respectively. These results indicate that AC has the potential to replace Pt as a very low cost counter electrode of bifacial DSSCs. The bifacial DSSC system using double plane mirrors improve PCE to for Pt counter electrode at a mirror angle of , and for AC counter electrode at a mirror angle of , respectively.

New approaches in component design for dye-sensitized solar cells

Dye solar cell based on Cu coordination complex as redox mediator and carbon counter electrode.

Chlorine management of a carbon counter electrode for high performance printable perovskite solar cells

The schematic of the effects of chlorinated graphite (C–Cl) on the interface of carbon and perovskite and the energy level alignment.

Efficient carbon counter electrodes for BaSnO3-based dye-sensitized solar cells

Natural source derived carbon materials make them ideally suited alternative to costly Pt counter electrode for their good catalytic activity, resistance to iodine corrosion, and high stability of the device. Apart from the extensively acclaimed photoanode TiO 2 , BaSnO 3 (BSO) has been projected as an efficient alternative to it. In this study, remarkable efforts have been endeavoured to establish BSO-carbon-based dye-sensitized solar cell (DSSC) device. Investigation on the adequate performance of natural source derived carbon-based counter electrodes for BSO-based DSSCs, explored as a significant alternative to costly Pt and TiO 2 , respectively, which could elucidate better photo-stability and more extended device performance compared to TiO 2 -Pt-based DSSCs.

Hysteresis Analysis of Hole-Transport-Material-Free Monolithic Perovskite Solar Cells with Carbon Counter Electrode by Current Density-Voltage and Impedance Spectra Measurements.

Due to the tremendous increase in power conversion efficiency (PCE) of organic–inorganic perovskite solar cells (PSCs), this technology has attracted much attention. Despite being the fastest-growing photovoltaic technology to date, bottlenecks such as current density–voltage (J–V) hysteresis have significantly limited further development. Current density measurements performed with different sweep scan speeds exhibit hysteresis and the photovoltaic parameters extracted from the current density–voltage measurements for both scan directions become questionable. A current density–voltage measurement protocol needs to be established which can be used to achieve reproducible results and to compare devices made in different laboratories. In this work, we report a hysteresis analysis of a hole-transport-material-free (HTM-free) carbon-counter-electrode-based PSC conducted by current density–voltage and impedance spectra measurements. The effect of sweep scan direction and time delay was examined on the J–V characteristics of the device. The hysteresis was observed to be strongly sweep scan direction and time delay dependent and decreased as the delay increased. The J–V analysis conducted in the reverse sweep scan direction at a lower sweep time delay of 0.2 s revealed very large increases in the short circuit current density and the power conversion efficiency of 57.7% and 56.1%, respectively, compared with the values obtained during the forward scan under the same conditions. Impedance spectroscopy (IS) investigations were carried out and the effects of sweep scan speed, time delay, and frequency were analyzed. The hysteresis was observed to be strongly sweep scan direction, sweep time delay, and frequency dependent. The correlation between J–V and IS data is provided. The wealth of photovoltaic and impendence spectroscopic data reported in this work on the hysteresis study of the HTM-free PSC may help in establishing a current density–voltage measurement protocol, identifying components and interfaces causing the hysteresis, and modeling of PSCs, eventually benefiting device performance and long-term stability.