scholarly journals Electrolyte Tuning in Iron(II)-Based Dye-Sensitized Solar Cells: Different Ionic Liquids and I2 Concentrations

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3053
Author(s):  
Mariia Becker ◽  
Catherine E. Housecroft ◽  
Edwin C. Constable

The effects of different I2 concentrations and different ionic liquids (ILs) in the electrolyte on the performances of dye-sensitized solar cells (DSCs) containing an iron(II) N-heterocyclic carbene dye and containing the I–/I3– redox shuttle have been investigated. Either no I2 was added to the electrolyte, or the initial I2 concentrations were 0.02, 0.05, 0.10, and 0.20 M. The short-circuit current density (JSC), open-circuit voltage (VOC), and the fill factor (ff) were influenced by changes in the I2 concentration for all the ILs. For 1-hexyl-3-methylimidazole iodide (HMII), low VOC and low ff values led to poor DSC performances. Electrochemical impedance spectroscopy (EIS) showed the causes to be increased electrolyte diffusion resistance and charge transfer resistance at the counter electrode. DSCs containing 1,3-dimethylimidazole iodide (DMII) and 1-ethyl-3-methylimidazole iodide (EMII) showed the highest JSC values when 0.10 M I2 was present initially. Short alkyl substituents (Me and Et) were more beneficial than longer chains. The lowest values of the transport resistance in the photoanode semiconductor were found for DMII, EMII, and 1-propyl-2,3-dimethylimidazole iodide (PDMII) when no I2 was added to the initial electrolyte, or when [I2] was less than 0.05 M. Higher [I2] led to decreases in the diffusion resistance in the electrolyte and the counter electrode resistance. The electron lifetime and diffusion length depended upon the [I2]. Overall, DMII was the most beneficial IL. A combination of DMII and 0.1 M I2 in the electrolyte produced the best performing DSCs with an average maximum photoconversion efficiency of 0.65% for a series of fully-masked cells.

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Chi-Hui Chien ◽  
Ming-Lang Tsai ◽  
Chi-Chang Hsieh ◽  
Yan-Huei Li ◽  
Yuh J. Chao

This work presents a novel light harvesting policy for a black counter electrode (BCE) to enhance the performance of dye-sensitized solar cells (DSSCs), which uses a metal-based light scattering layer (MLSL) that is formed from Al@SiO2 core-shell microflakes prepared and coated on BCE. DSSCs based on BCE with and without the MLSL are compared as well. Analysis results of electrochemical impedance spectra (EIS) indicate that, while not affecting the charge transfer resistance at BCE, MLSL exhibits a low electron transport resistance in the TiO2/electrolyte interface. Our results further demonstrate that MLSL reflects light to the TiO2 electrode, subsequently increasing photocurrent density by 68.68% (from 2.65 to 4.47 mA/cm2) and improving the power conversion efficiency by 49.64%.


2011 ◽  
Vol 347-353 ◽  
pp. 390-393 ◽  
Author(s):  
Shun Jian Xu ◽  
Yu Feng Luo ◽  
Wei Zhong ◽  
Guan Jun Qiao

A novel counter electrode has been fabricated at low temperature using nanoporous carbon (NC) with about 35 nm pore size as based catalysis materials and silver conductor paste (SCP) as connecting adhesive. The efficiency of dye-sensitized solar cells (DSCs) employing this SCP/NC electrode reaches to 5.91%, which is 15% higher than that of DSCs with NC electrode. The improved efficiency is attributed to the enhancement in the fill factor and the short circuit photocurrent density. Electrochemical impedance spectroscopy reveals that all of charge transfer resistance, ohmic serial resistance and Nernst diffusion impedance of SCP/NC electrode decrease compared with NC electrode. Especially, the efficiency of 5.91% is comparable to that of DSCs with Pt electrode.


2012 ◽  
Vol 512-515 ◽  
pp. 242-245 ◽  
Author(s):  
Shun Jian Xu ◽  
Yu Feng Luo ◽  
Wei Zhong ◽  
Zong Hu Xiao ◽  
Xiao Yun Liu

Hexagonal boron nitride (HBN), which has the same crystal structure as graphite, has been used as catalytic material for a counter electrode in dye-sensitized solar cells (DSCs) to investigate its potential application. X-ray diffraction (XRD) has been used to confirm the crystal structure of HBN, scanning electron microscopy (SEM) has been used to characterize the morphology of HBN film on counter electrode, and electrochemical workstation has been employed to obtain the electrochemical impedance spectroscopy (EIS) and corresponding impedance parameters. Results show that the HBN film has rough surface and porous structure with pore size of less than 1 μm. When employed the HBN counter electrode to DSCs, the conversion efficiency (η) is only about a tenth of that of graphite based DSCs. Low efficiency of HBN based DSCs is induced by high charge transfer resistance (Rct) of HBN counter electrode, which means that HBN can hardly provide catalytic activity for the reduction of the triiodide ion. Therefore, the crystal structure is not a crucial factor to select the catalytic material for a counter electrode in DSCs. Moreover, the short circuit photocurrent density (Jsc) and the open circuit voltage (Voc) of device also evidently depend on the characteristics of catalytic material.


2010 ◽  
Vol 20 (9) ◽  
pp. 1654 ◽  
Author(s):  
Shahzada Ahmad ◽  
Jun-Ho Yum ◽  
Zhang Xianxi ◽  
Michael Grätzel ◽  
Hans-Jürgen Butt ◽  
...  

2011 ◽  
Vol 685 ◽  
pp. 1-5 ◽  
Author(s):  
Gui Qiang Wang ◽  
Wei Xing ◽  
Shu Ping Zhuo

Hierarchical porous carbons (HPC) were synthesized by a combination of self-assembly and chemical activation method. A mesoporous carbon with large-size pore was used as raw materials. N2sorption measurement indicated that plenty of micropores generated within the mesopore wall in the mesoporous carbon during KOH activation. Electrochemical impedance spectroscopy measurement demonstrated a high electrocatalytic activity of HPC electrode for triiodide reduction. The overall conversion efficiency of dye-sensitized solar cells with HPC counter electrode was 6.48%, which is similar to that of the device with conventional Pt counter electrode.


2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Le Thanh Nguyen Huynh ◽  
Viet Hai Le ◽  
Thanh Long Vo ◽  
Thi Kim Lan Nguyen ◽  
Quoc Hien Nguyen ◽  
...  

Nano-silver-titanium dioxide (Ag-TiO2) composites were prepared from commercial TiO2 (P25, Degussa) and silver nitrate (AgNO3) by gamma Co-60 irradiation method with various initial concentrations of AgNO3. The nano-AgTiO2 composites are utilized as the photoanode for dye-sensitized solar cells (DSCs). Under full sunlight illumination (1000 W/m2, AM 1.5), the efficiency of DSCs has improved significantly despite the Ag content of below 1%. The DSC—assembled with 0.75 Ag-TiO2 (0.75% Ag) photoanode—showed that the photocurrent was significantly enhanced from 8.1 mA.cm−2 to 9.5 mA.cm−2 compared to the DSCs using bared TiO2 photoanode. The unchanged open-circuit voltage resulted in the overall energy conversion efficiency to be increased by 25% from 3.75% to 4.86%. Electrochemical impedance spectroscopy (EIS) analysis showed that the charge transfer resistance is reduced when increasing Ag content, demonstrating that the charge transfer at TiO2/dye interface was enhanced in the presence of silver nanoparticles.


Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1725 ◽  
Author(s):  
Zhi Zeng ◽  
Dongbo Wang ◽  
Jinzhong Wang ◽  
Shujie Jiao ◽  
Yuewu Huang ◽  
...  

In this work, MoS2 microspheres/PtCo-alloy nanoparticles (MoS2/PtCo-alloy NPs) were composited via a novel and facile process which MoS2 is functionalized by poly (N-vinyl-2-pyrrolidone) (PVP) and self-assembled with PtCo-alloy NPs. This new composite shows excellent electrocatalytic activity and great potential for dye-sensitized solar cells (DSSCs) as a counter electrode (CE) material. Benefiting from heterostructure and synergistic effects, the MoS2/PtCo-alloy NPs exhibit high electrocatalytic activity, low charge-transfer resistance and stability in the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) test. Meanwhile, a high power-conversion efficiency (PCE) of 8.46% is achieved in DSSCs with MoS2/PtCo-alloy NP CEs, which are comparable to traditional Pt CEs (8.45%). This novel composite provides a new high-performance, stable and cheap choice for CEs in DSSCs.


2013 ◽  
Vol 750-752 ◽  
pp. 923-926
Author(s):  
Shun Jian Xu ◽  
Yu Feng Luo ◽  
Wei Zhong ◽  
Zong Hu Xiao ◽  
Yong Ping Luo ◽  
...  

Four types of graphene nanosheets (GNs) with different graphene layer number were employed to fabricate counter electrode for dyesensitized solar cells (DSCs), with emphasis on understanding the influence of graphene layer number on the properties of the counter electrode and the device. The results show that with the graphene layer number of the GNs increases from 3 to 8, both efficiency and fill factor of the GNs based DSCs firstly climb and reach a peak at 6 of graphene layer number, and then decline with further increasing. Electrochemical impedance spectroscopy (EIS) reveals that when the graphene layer number of the GNs increases from 3 to 6, the decreased sheet resistance of the electrode and the strengthened capability of electrolyte diffusion in the electrode result in the improvement of the photovoltaic performances of the DSCs. However, when the graphene layer number further ascends to 8, the weakened capabilities of both catalytic activity of the electrode for the reduction and electrolyte diffusion in the electrode lead to the poor photovoltaic performances of the device.


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