ZnO/TiO2 composite photoanodes for efficient dye-sensitized solar cells

2014 ◽  
Vol 07 (04) ◽  
pp. 1450039 ◽  
Author(s):  
Liqing Zhang ◽  
Shuai Zhou ◽  
Fengshi Cai ◽  
Zhihao Yuan

ZnO / TiO 2 composite films composed of a ZnO nanoflowers overlayer and a ZnO / TiO 2 composite particulate underlayer were fabricated by a simple hydrothermal process. The as-prepared films were characterized by scanning electron microscopy, transmission electron microscopy (TEM) and diffused reflectance spectroscopy. The performance of dye-sensitized solar cells (DSCs) was investigated by photocurrent–voltage measurements, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy. It was found that the ZnO / TiO 2 composite film prepared with a 60 min growth time exhibited higher reflectivity than that of pure TiO 2 film due to the effective light-scattering of ZnO nanoflowers, resulting in increased J sc . In the meantime, the open-circuit potential of the device were enhanced from 698 to 826 mV due to the formation of an energy barrier by ZnO at TiO 2/electrolyte interface, resulting in a 52% improvement in the power conversion efficiency from 4.64 to 7.06%.

NANO ◽  
2014 ◽  
Vol 09 (06) ◽  
pp. 1450061 ◽  
Author(s):  
MUHAMMAD SALEEM ◽  
L. FANG ◽  
M. ASHFAQ AHMAD ◽  
RIZWAN RAZA ◽  
F. WU ◽  
...  

Zinc oxide ( ZnO ) nanowire (NW) films were synthesized at low temperature (95°C) through amine-assisted solution process and used as photoanode for the fabrication of dye-sensitized solar cells (DSSCs). It was found that with the addition of polyethyleneimine (PEI) and ammonium hydroxide ( NH 4 OH ) in growth solution, the NWs were smaller in diameter and longer in length by prolonging the growth time without refreshing the growth solution. A reasonable overall conversion efficiency of 1.25% was achieved with photoanode based on ZnO NWs containing PEI and NH 4 OH . However, DSSC fabricated with ZnO NWs not containing PEI and NH 4 OH showed low conversion efficiency of 0.58%. All the DSSCs exhibited almost similar values of open circuit voltage (V OC ) and fill factor (FF). Interestingly, DSSC based on ZnO NWs with PEI and NH 4 OH obtained two times higher short circuit current density (J SC ) compared to ZnO NWs photoanode without PEI and NH 4 OH . The increase in efficiency and J SC with the length of NWs is attributed to the increase in internal surface area for sufficient dye loading and light harvesting.


MRS Advances ◽  
2019 ◽  
Vol 4 (08) ◽  
pp. 481-489
Author(s):  
Jihun Kim ◽  
Horim Lee ◽  
Dong Young Kim ◽  
Sehyun Kim ◽  
Yongsok Seo

AbstractWe have developed new flexible dye-sensitized solar cells (DSSCs) comprising organic dye (JH-1), cobalt redox electrolyte and hierarchically structured TiO2 (HS-TiO2) photoelectrode prepared using an electrostatic spray method. The performance of JH-1 sensitized flexible DSSC with a cobalt redox electrolyte was compared with those of N719-based DSSC and DSSC with I-/ I3- redox electrolyte. As a result, JH-1 sensitized flexible DSSC with [Co(Ⅲ/Ⅱ)(bpy-pz)3](PF6)3/2 redox system exhibited a high photocurrent density of 9.17 mA cm-2, an open circuit voltage of 0.953 V, a fill factor of 0.70, and a power conversion efficiency of 6.12% under 1 sun illumination (100 mW cm-2). The incident photon-to-current conversion efficiency was measured to explain the photocurrent generation difference by different dyes and electrolytes. The electron recombination lifetime of cells was measured by intensity-modulated photovoltage spectroscopy. Mass transport in DSSCs employing cobalt redox electrolytes was also investigated by the photocurrent transient measurements and electrochemical impedance spectroscopy (EIS) analysis.


Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1645 ◽  
Author(s):  
Seong Il Cho ◽  
Hye Kyeong Sung ◽  
Sang-Ju Lee ◽  
Wook Hyun Kim ◽  
Dae-Hwan Kim ◽  
...  

At an elevated temperature of 90 °C, a chemical bath deposition using an aqueous solution of Zn(NO3)2·6H2O and (CH2)6N4 resulted in the formation of both nanoflowers and microrods of ZnO on F-doped SnO2 glass with a seed layer. The nanoflowers and microrods were sensitized with dyes for application to the photoelectrodes of dye-sensitized solar cells (DSSCs). By extending the growth time of ZnO, the formation of nanoflowers was reduced and the formation of microrods favored. As the growth time was increased from 4 to 6 and then to 8 h, the open circuit voltage (Voc) values of the DSSCs were increased, whilst the short circuit current (Jsc) values varied only slightly. Changes in the dye-loading amount, dark current, and electrochemical impedance were monitored and they revealed that the increase in Voc was found to be due to a retardation of the charge recombination between photoinjected electrons and I3− ions and resulted from a reduction in the surface area of ZnO microrods. A reduced surface area decreased the dye contents adsorbed on the ZnO microrods, and thereby decreased the light harvesting efficiency (LHE). An increase in the electron collection efficiency attributed to the suppressed charge recombination counteracted the decreased LHE, resulting in comparable Jsc values regardless of the growth time.


Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4181 ◽  
Author(s):  
Mariia Karpacheva ◽  
Vanessa Wyss ◽  
Catherine E. Housecroft ◽  
Edwin C. Constable

By systematic tuning of the components of the electrolyte, the performances of dye-sensitized solar cells (DSCs) with an N-heterocyclic carbene iron(II) dye have been significantly improved. The beneficial effects of an increased Li+ ion concentration in the electrolyte lead to photoconversion efficiencies (PCEs) up to 0.66% for fully masked cells (representing 11.8% relative to 100% set for N719) and an external quantum efficiency maximum (EQEmax) up to approximately 25% due to an increased short-circuit current density (JSC). A study of the effects of varying the length of the alkyl chain in 1-alkyl-3-methylimidazolium iodide ionic liquids (ILs) shows that a longer chain results in an increase in JSC with an overall efficiency up to 0.61% (10.9% relative to N719 set at 100%) on going from n-methyl to n-butyl chain, although an n-hexyl chain leads to no further gain in PCE. The results of electrochemical impedance spectroscopy (EIS) support the trends in JSC and open-circuit voltage (VOC) parameters. A change in the counterion from I− to [BF4]− for 1-propyl-3-methylimidazolium iodide ionic liquid leads to DSCs with a remarkably high JSC value for an N-heterocyclic carbene iron(II) dye of 4.90 mA cm−2, but a low VOC of 244 mV. Our investigations have shown that an increased concentration of Li+ in combination with an optimized alkyl chain length in the 1-alkyl-3-methylimidazolium iodide IL in the electrolyte leads to iron(II)-sensitized DSC performances comparable with those of containing some copper(I)-based dyes.


2011 ◽  
Vol 1303 ◽  
Author(s):  
Xuan Pan ◽  
Yong Zhao ◽  
Changhong Chen ◽  
Zhaoyang Fan

ABSTRACTThe titanium dioxide (TiO2) nanoparticle (NP) structure has higher surface area and dye loading value to increase photon absorption while the nanotube (NT) can suppress the random walk phenomena to enhance carrier collection. In this work, hydrothermal method was utilized to infiltrate the TiO2 nanotube array by TiO2 nanoparticles with the aim of combining the advantages of both nanostructures to improve dye sensitized solar cells (DSSCs) efficiency. Structure morphology, device performance, and electrochemical properties were investigated. SEM observation confirmed that around 10 nm TiO2 nanoparticles uniformly covered the NT wall. TiO2 NT samples at three different lengths: 8 μm, 13 μm and 20 μm, decorated with different amount of nanoparticles were studied to optimize the structure for light absorption and electron transport to achieve high solar conversion efficiency. Electrochemical impedance spectroscopy (EIS) was also employed to investigate the cells’ parameters: electron lifetime (τ), diffusion length (Ln) et al, to gain insight on the device performance. The incident photon conversion efficiency (IPCE) was also reported.


2016 ◽  
Vol 675-676 ◽  
pp. 158-162 ◽  
Author(s):  
Sanpet Nilphai ◽  
Meechai Thepnurat ◽  
Niyom Hongsith ◽  
Pipat Ruankham ◽  
Surachet Phadungdhitidhada ◽  
...  

Magnesium oxide (MgO) nanostructures were synthesized by microwave-assisted thermal oxidation at various amount of activated carbon additive. The MgO nanostructures were characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffractrometry (XRD) and UV-Visible spectroscopy, respectivly. It was observed that, the obtained MgO have nanocube shape. The MgO nanostructures were applied as a blocking layer in ZnO dye-sensitized solar cells (DSSC). The photovoltage, photocurrent, and power conversion efficiency characteristics of DSSCs were measured under illumination of simulated sunlight obtained from a solar simulator with the radiant power of 100 mW/cm2. The DSSCs with MgO layer exhibited higher current density, open circuit voltage and photoconversion efficiency than those without MgO layer The optimum power conversion efficiency (PCE) was 2.49 % with short circuit current (Jsc) of 6.61 mA/cm2, the open circuit voltage (Voc) of 0.66 V and the fill factor (FF) of 0.59, respectively.


2008 ◽  
Vol 8 (9) ◽  
pp. 4761-4766 ◽  
Author(s):  
Dong Wook Kim ◽  
Jin Joo Choi ◽  
Man Ku Kang ◽  
Yongku Kang ◽  
Changjin Lee

We prepared organic sensitizers (S1 and S2) containing julolidine moiety as a donor, phenyl or phenylene thiophene units as a conjugation bridge, and cyano acetic acid as an acceptor for dye sensitized solar cells. S1 exhibited two absorption maxima at 441 nm (ε = 26 200) and 317 nm (ε = 15 500) due to the π–π* transition of the dye molecule. S2 dyes with an additional thiophene unit showed the absorption maximum extended by 18 nm. DSSCs based on S1 dye achieved 2.66% of power conversion efficiency with 8.3 mA cm−2 of short circuit current, 576 mV of open circuit voltage, and 0.56 of fill factor. DSSCs using S2 dye with a longer conjugation attained only 1.48% of power conversion efficiency. The 0.21 V lower driving force for regeneration of the S2 dye compared to the S1 dye is one of the reasons for low conversion efficiency of the S2 dye.


2021 ◽  
Author(s):  
S. Revathi ◽  
A Pricilla Jeyakumari

Abstract Currently, the TiO2/CdS photoanodes based dye sensitized solar cells (DSSCs) have shown extraordinary developments in the photo conversion efficiency. In this report, pristine TiO2, CdS and various molar ratios of TiO2/CdS photoanodes were prepared by one step microwave irradiation route and followed by doctor blade method. The sheet like morphology of the TiO2 and CdS nanoparticles were clearly evident from the SEM and TEM images. A significant reduction band gap with enhanced light absorption and rapid prevention of electron hole pair was explored by UV-DRS and PL studies. The photocurrent density-voltage (J-V) and electrochemical impedance (EIS) characteristics were analyzed for assembled solar cell. The photo-conversion efficiency of 12.8% was obtained with the configuration TiO2/CdS (200 mg) that represent a 2.5 fold increment compared to bare TiO2 (5.33%) as well as commercial Pt (6.11%). The experimental results are discussed.


2021 ◽  
Vol 2101 (1) ◽  
pp. 012066
Author(s):  
Hao Yang ◽  
Hao Fan ◽  
Junhong Duan

Abstract In this work, Mg-doped SnO2 materials with different molar ratios were synthesized by hydrothermal method. Based on the UV-Vis study, band gap (Eg) of the Mg-doped SnO2 is adjusted from 3.76 eV to 3.65 eV via 3 at% concentrations. Results of photovoltaic measurement for dye-sensitized solar cells (DSCs) based on Mg-doped SnO2 film as photoanode indicate that the doping of Mg ions can improve the open-circuit voltage (V oc) of the DSCs, while the electric current density (J sc) of the DSCs is almost unchanged. The cells were measured at 3 days intervals within 24 days after fabrication. Power conversion efficiency (PCE) of 3 at% Mg-doped SnO2 DSCs increases step by step and achieves 4.38% as the cell is tested after 18 days. Electrochemical impedance spectroscopy (EIS) analysis shows that Mg doping enhances light collection, increased the number of photogenerated electrons and inhibits charge recombination.


2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Joe Otsuki ◽  
Yusho Takaguchi ◽  
Daichi Takahashi ◽  
Palanisamy Kalimuthu ◽  
Surya Prakash Singh ◽  
...  

We have prepared a novel piperidine-donor-substituted perylene sensitizer, PK0002, and studied the photovoltaic performance in dye-sensitized solar cells (DSSCs). Physical properties and photovoltaic performance of this new perylene derivative PK0002 are reported and compared with those of unsubstituted perylene sensitizer, PK0003. PK0002, when anchored to nanocrystalline TiO2 films, achieves very efficient sensitization across the whole visible range extending up to 800 nm. The incident photon-to-current conversion efficiency (IPCE) spectrum was consistent with the absorption spectrum and resulted in a high short-circuit photocurrent density (Jsc) of 8.8 mA cm-2. PK0002 showed higher IPCE values than PK0003 in the 520–800 nm region. Under standard AM 1.5 irradiation (100 mW cm-2) and using an electrolyte consisting of 0.6 M dimethylpropyl-imidazolium iodide, 0.05 M I2, 0.1 M LiI, and 0.5 M tert-butylpyridine in acetonitrile, a solar cell containing sensitizer PK0002 yielded a short-circuit photocurrent density of 7.7 mA cm-2, an open-circuit photovoltage of 0.57 V, and a fill factor of 0.70, corresponding to an overall conversion efficiency of 3.1%.


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