Band Tunable CdSe Quantum Dot-Doped Metals for Quantum Dot-Sensitized Solar Cell Application

Phuc, Dang Huu; Tung, Ha Thanh

doi:https://doi.org/10.1155/2019/9812719

International Journal of Photoenergy

On this page

Abstract Introduction Results and Discussion Conclusions Data Availability Conflicts of Interest Acknowledgments Supplementary Materials References Copyright Related Articles

Special Issue

Advanced Nanomaterials and Nanotechnologies for Solar Energy

View this Special Issue

Research Article | Open Access

Volume 2019 | Article ID 9812719 | https://doi.org/10.1155/2019/9812719

Band Tunable CdSe Quantum Dot-Doped Metals for Quantum Dot-Sensitized Solar Cell Application

Dang Huu Phuc^1,2and Ha Thanh Tung³

Guest Editor: Wei Wei

Received17 Nov 2018

Accepted25 Dec 2018

Published25 Feb 2019

Abstract

Quantum dots are drawing great attention as a material for the next-generation solar cells because of the high absorption coefficient, tunable band gap, and multiple exciton generation effect. In search of the viable way to enhance the power conversion efficiency of quantum dot-sensitized solar cells, we have succeeded in preparing the quantum dot solar cells with high efficiency based on CdSe:X (Mn²⁺ or Cu²⁺) nanocrystal by successive ionic layer absorption and reaction. The morphological observation and crystalline structure of photoanode were characterized by field-emission scanning electron microscopy, X-ray diffraction, and the EDX spectra. In addition, the electrochemical performance of photoelectrode was studied by the electrochemical impedance spectra. As a result, we have succeeded in designing QDSSCs with a high efficiency of 4.3%. Moreover, the optical properties, the direct optical energy gap, and both the conduction band and the valence band levels of the compositional CdSe:X were estimated by the theory of Tauc and discussed details. This theory is useful for us to understand the alignment energy structure of the compositions in electrodes, in particular, the conduction band and valence band levels of CdSe:X nanoparticles.

1. Introduction

In recent years, inorganic semiconductor materials, which are also called Quantum Dots (QDs), have emerged as a powerful light-absorbing material that generates electrons for the quantum dot-sensitized solar cell (QDSSC) application. Various QDs were applied in the QDSSCs such as CdS, CdSe [1], PbS, PbSe [2, 3], and InP [1]. These had a number of advantages over dye molecules because the band gap could be controlled through particle size, modification [4], the high optical absorption coefficient [5], and generating several e–h⁺ pairs as absorbing photons [6]. So far, QDSSCs have still low optical conversion efficiency compared to dye-sensitized solar cells [7–11].

There are now a number of ways to improve performance of QDSSCs such as QDSSCs based on the CdS/CdSe combination synthesized by chemical bath deposition methods and successive ionic layer absorption and reaction (SILAR) adsorbed directly onto TiO₂ nanoparticles [12, 13]. The improved performance was also achieved on core-shell QDs. Yu et al. reported the fabrication results on the CdS/CdSe core-shell system, resulting in higher current density, voltage, and performance than single QDs [13]. Yu said that the improved performance was done because of the reduced recombination processes at the surface trapping states of QDs and the increased electron mobility to TiO₂ nanoparticles. In addition, the combination of electrons and holes in the contact surfaces and in semiconductor oxides such as TiO₂ and ZnO causes the reduction in performance of QDSSCs. To reduce the recombination processes, Jung and colleagues coated CdS QDs with a ZnS layer to protect QDs from the electrolyte [14–16]. This result was also confirmed in the QDSSCs based on PbS QDs with a CdS protection layer [17]. There were many methods that can reduce recombination in devices, but the most common method of surface treatment was used. Surface treatment means protection of QDs, which helped stabilize QDs in an electrolyte solution [18, 19].

Today, CdSe QDs are widely used by scientists in QDSSCs because of their easy manufacture, low cost, and high stability. However, their resistance is high and their CB energy is lower than that of TiO₂ in the bulk material. These results do not facilitate the shift of electrons from CdSe QDs to the TiO₂ film. By doping metal ions into QDs such as Cu [6], In [20], Co [21], Mn [22, 23], Hg [24], Eu [25, 26], La [27], and Mg [28], the electrical and optical properties of photoanode can be improved by the boosting absorption of photons of QDSSCs.

As far as reasons are concerned, QDSSCs based on X ions doped on CdSe nanoparticles with the different compositions of the Mn²⁺ ( between 0% and 40%) and the Cu²⁺ ( from 0% to 0.5%) by SILAR were illustrated. Moreover, the significant effects of X dopant on optical, physical, chemical, and photovoltaic properties of QDSSCs can be studied by the UV-Vis spectra and Tauc equation, which can determine the , CB, and VB positions of X ions doped on pure CdSe nanoparticles. This theory is useful for us to understand the alignment energy structure of the compositions in electrodes, in particular, CB and VB levels of CdS, CdSe:X nanoparticles. As a result, there is a rise or a drop of the CB and the VB levels when X content was changed. Correspondingly, the electrochemical impedance spectra were carried out to determine dynamic resistances in QDSSCs.

2. Experiment

In this experiment, TiO₂/CdS and TiO₂/CdS/CdSe:Cu²⁺ were synthesized similar to Ref [29]. In Ref [29], the thickness of TiO₂/CdS/CdSe:Cu²⁺ was investigated to get the optimization. However, in this paper, we investigated the effect of Cu²⁺ molar concentrations as doping it into CdSe nanoparticle. Besides, we also prepared QDSSCs based on Mn²⁺ ion-doped CdSe nanoparticle and compared with that of QDSSCs based on TiO₂/CdS/CdSe:Cu²⁺ photoanode.

2.1. TiO₂ and TiO₂/CdS Films Were Prepared As Follows Ref [29]

Briefly, a fluorine-doped tin oxide (FTO) glass substrate with sheet resistance 7 Ωsq⁻² was used for the photoanode and the counter electrode. First, the FTO substrate was cleaned with ethanol for 30 min by ultrasonic, followed by deionized (DI) water for 15 min. The nanoporous TiO₂ film was made on the well-cleaned substrate by the print method followed by sintering at 500°C for 30 min. TiO₂/CdS film: TiO₂ films were dipped into a Cd(CH₃COO)₂·2H₂O ethanol solution for 5 min, rinsed with ethanol, and dried, then successively dipped into a Na₂S·9H₂O methanol solution for another 5 min, rinsed with methanol, and dried. The two-step dipping procedure was termed as one SILAR cycle. The process was repeated three times, and the obtained TiO₂ film decorated with CdS QDs was named as the TiO₂/CdS film [30].

2.2. A TiO₂/CdS/CdSe:Mn²⁺ Film

Similarly, the Mn doped on CdSe QDs was attached to the TiO₂/CdS film using SILAR. 0.740304 g Cd(NO₃)₂·2H₂O and 0.47054 g Mn(CH₃COO)₂·2H₂O were dissolved in 30 ml ethanol and DI water with ratio 1 : 1 to obtain 0.1 M of Cd²⁺ and Mn²⁺ solution. The process involved subsequent immersions of the TiO₂/CdS film in a solution of 0.1 M of Cd²⁺ and Mn²⁺ solution for 5 min and then rinsed with ethanol. It then was immersed in 0.3 M of Se^2- solution for 5 min at 50°C and rinsed with DI water. To accommodate the doping of Mn²⁺ ion, relevant molar concentrations of 0.1 mM, 0.2 mM, 0.3 mM, 0.4 mM, and 0.5 mM of Mn(CH₃COO)₂·2H₂O were mixed with Cd(CH₃COO)₂·2H₂O anion source. The process was repeated 3 times and the obtained TiO₂/CdS film decorated with CdS/Mn-CdSe multilayers.

2.3. A TiO₂/CdS/CdSe:Cu²⁺ Film

Preparation of TiO₂/CdS/CdSe:Cu²⁺ photoanodes: briefly, the TiO2/CdS layers were immersed into Cd²⁺ and Cu²⁺ ionized solution (molar concentrations of 0.1 mM, 0.2 mM, 0.3 mM, 0.4 mM, and 0.5 mM of Cu(NO₃)₂·3H₂O were mixed with Cd(CH₃COO)₂·2H₂O anion source) for 5 min at room temperature, then rinsed with ethanol to remove excess precursors and dried. The films were next dipped into Se^2- solution for 5 min at room temperature followed by rinsing with methanol and drying. This cycle was repeated 3 times [30]. The polysulfide electrolyte and Cu₂S counter electrode were followed Ref [30].

2.4. Characterization

Field-effect scanning electron microscope (FESEM, 7401F) of Ho Chi Minh City Institute of Physics was used to investigate the surface morphology and composition of photoanode using the voltage of 10 kV. The UV-Vis spectra were characterized by the JASCO V-670 device of Applied Physical Chemistry Lab of University of Science, Vietnam National University-Ho Chi Minh City. The crystal structure was analyzed using an X-ray diffractometer (Philips, PANalytical X’Pert, CuK_radiation) and photocurrent-voltage measurements were performed on a Keithley 2400 source meter using simulated AM 1.5 sunlight with an output power of produced by a solar simulator (Solarena, Sweden). The electrochemical impedance spectroscopy (EIS) was carried out with the use of an impedance analyzer (ZAHNER CIMPS).

3. Results and Discussion

Figures 1(a) and 1(d) are FESEM images of TiO₂/CdS/CdSe:Mn²⁺ and TiO₂/CdS/CdSe:Cu²⁺ photoanodes with 20% and 0.3% doping concentration, respectively. The highly porous nearly spherical-shaped TiO₂ nanoparticles can be observed very clearly from Figures 1(a) and 1(d) with an average size of approximately 70 nm. We can clearly see each layer of film, thickness of the FTO layer about 0.563 nm. The thickness of TiO₂/CdS/CdSe:Mn²⁺ and TiO₂/CdS/CdSe:Cu²⁺ photoanodes is approximately 12.056 μm and 12.675 μm, respectively. However, we did not observe both CdSe:Mn²⁺ and CdSe:Cu²⁺nanoparticles in the film because of their very small size. They can be filled in the space between the TiO₂ nanoparticles and absorbed onto the TiO₂ surface.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

The compositional EDX analysis of the CdSe:X is shown in Figures 1(c) and 1(f), which confirm the presence of Mn²⁺ and Cu²⁺ dopant in photoanodes. As can be seen from Figures 1(g) and 1(h), they are the same structures of TiO₂, CdS, and CdSe:Mn²⁺ (Cu²⁺). It is immediately obvious that the Raman spectroscopy of TiO₂/CdS/CdSe:Mn²⁺ electrode shows the modes at 144 cm^-1, 395 cm^-1, 515 cm^-1, and 636 cm^-1positions corresponding to the TiO₂ anatase [31]. Similarly, the above modes of TiO₂ anatase in the Raman spectroscopy of TiO₂/CdS/CdSe:Cu²⁺ electrode appear at 206 cm^-1, 266 cm^-1, 414 cm^-1 and 622 cm^-1positions. It is immediately obvious that there was a shift of the modes towards the high frequency due to the increase of CdSe:Cu²⁺-TiO₂ associate compared to CdSe:Mn²⁺-TiO₂ associate. Besides, there are one Longitudinal-Optical (1LO) and 2LO modes of CdSe:Mn²⁺ Zinc Blende at 201 cm^-1 and 395 cm^-1positions. However, the modes are shifted towards high frequency for Cu²⁺ ion-doped CdSe QDs. In addition, the 2LO mode of CdSe Cubic is shown in both Figures 1(g) and 1(h), but there was no 1LO mode. This implies that CdS, CdSe:Cu²⁺(Mn²⁺) nanoparticles have absorbed on TiO₂ films.

To determine the of the TiO₂/CdS/CdSe:Mn²⁺ and TiO₂/CdS/CdSe:Cu²⁺ electrodes, UV-Vis absorption measurements are carried out. By analysis of the absorption coefficients for the electrodes, optical energy gap can be estimated using Tauc plot of versus (hv) and extrapolating of the linear portions of the curves to the energy axis according to [32]

is the absorption coefficient, which is determined by about 9.10⁴ cm^-1 [33], where is the thickness of the film and is the transmittance; is the reflectance. hv is the photon energy, is the direct band gap energy, and is a constant (about 2.059 10^-2 cm^-1) [33]. The Tauc plots are shown in Figure 2.

(a)

(b)

(c)

(d)

Moreover, the CB and VB of CdS, CdSe nanoparticles can also be determined by Tauc equation. The CB and VB of materials can be calculated if the electron affinity energy and the ionization energy are known. Similarly, the CB and VB of CdS and CdSe can be determined by Tauc equation [34]. The calculated parameters are listed in Tables 1 and 2.

Optical properties of undoped and doped photoanodes, which were prepared by SILAR method and calcined in a vacuum environment, were investigated by UV-Vis absorption spectra. Figures 2(a) and 2(b) show the UV-Vis absorption spectra of the photoelectrode with undoped (, ) and doped concentration of Mn²⁺ ions from 5% to 40% and Cu²⁺ ions from 0.1% to 0.5%. In general, there are two major differences between UV-Vis absorption spectra of undoped films and doped films such as, firstly, there is a very sharp increase in absorption spectra intensity when we doped Mn²⁺ ions from 5% to 40% and Cu²⁺ ions from 0.1% to 0.5% on CdSe QDs. This implied that the presence of metal ion energy levels in the band gap of CdSe QDs causes an increase in the absorption of incoming photons [35]. This result will be explained in more detail when we determine the CB energy and the VB of both CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs. Secondly, there is a shift of the absorption peak in the red region compared to the undoped photoelectrodes (from 570 nm to 615 nm) [36–38]. This is also understandable because of the change in band gap of CdSe QDs after doping; the CB position of CdSe QDs may be raised and its band gap may be narrowed. Figures 2(c) and 2(d) show the Tauc plot of Mn²⁺ ions from 5% to 40% and Cu²⁺ ions from 0.1% to 0.5% on CdSe QDs as shown in Tables 1 and 2. The band gap values of both CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs reduced compared to the band gap of pure CdSe QDs.

Figure 3 shows photocurrent density-voltage curves of QDSSCs based on the metal ion-doped photoanodes measured under AM 1.5, 100 mW/cm², and the photovoltaic parameters are listed in Table 3. The QDSSCs on undoped TiO₂/CdSe films were measured with open circuit (), FF (0.38), short-current density (), and efficiency (). In general, the QDSSCs based on CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs have better performance compared to the QDSSCs based on undoped films. When doping, open-circuit parameters, short-circuit currents, and efficiency increase due to the conduction band position of CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs, which is raised higher than that of TiO₂ semiconductor and listed in Tables 1 and 2. Similar to the UV-Vis absorption spectra, there was a strong increase in efficiency of the QDSSCs from 1.95% (with pure CdSe QDs) to 4.3% (with CdSe:Cu²⁺ QDs) and 3.8% (CdSe:Mn²⁺ QDs). The result of an increase performance is due to the effect of metal concentration impurities in CdSe QDs. This result is also explained by the calculation of CB energy levels, the VB of TiO₂ semiconductor, CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs [29, 39]. As we know, in the bulk material, the CB position of CdSe QDs (-4.5 eV) is lower than the CB of TiO₂ (-4.3 eV), which is difficult for excited electrons to move from CdSe QDs to TiO₂ nanoparticles [27]. However, after doping, the CB energy of CdSe:Mn²⁺ and CdSe:Cu²⁺ QDs is significantly increased from -4.5 eV to -4.05 eV (for CdSe:Cu²⁺ QDs) and -3.74 eV (for CdSe:Mn²⁺ QDs), which is higher than the CB of TiO₂ nanoparticles. Therefore, like a waterfall, electrons can easily move from CdSe:X QDs to TiO₂ film. This result also causes an increase in current density from 12.5 mA to 20 mA (CdSe:Cu²⁺ QDs) and 19 mA (CdSe:Mn²⁺ QDs).

(a)

(b)

Figures 4(a) and 4(b) are the EIS curves of photoanodes with the doped concentration of Mn²⁺ ions from 5% to 40% and Cu²⁺ ions from 0.1% to 0.5% under one-sun illumination and open circuit of the device; the parameter values shown are in Tables 3 and 4. Basically, the EIS curves have two semicircles corresponding to the resistance at the surface of the polyelectrolyte/counter electrode (denoted as ) and the diffuse resistance in the TiO₂ film and TiO₂/CdSe:X surface (denoted as ) [40]. After measuring the EIS curve, we used Nova software to fit and obtain the circuit corresponding to each EIS curve. From the circuit obtained, we determined and resistances, respectively. The lifetime of the excited electron () is determined by the formula , and the capacitance of QDSSCs () is determined by . The calculated values are presented in Tables 3 and 4. In general, the QDSSCs based on TiO₂/CdSe:Mn²⁺ with the doped concentration from 5% to 40% and TiO₂/CdSe:Cu²⁺ with the doped concentration from 0.1% to 0.5% have sharply changed the photovoltaic, which causes the change of and resistance values, the capacitance, and the excited electron lifetime of CdSe:X QDs. In particular, the and resistances correspond to pure CdSe QDs recorded approximately 630.5 Ω and 194.8 Ω; they are much higher than both the (254.4 Ω) and (8.68 Ω) resistances with the Cu²⁺-doped concentration from 0.1% to 0.5% and the (204.5 Ω) and (24.65 Ω) resistances with the Mn²⁺-doped concentration from 10% to 40%, while the excited electron lifetime and capacitances of QDSSCs are much lower [29]. This result implies that Cu²⁺ and Mn²⁺ doping into CdSe QDs can cause a decrease in diffusion resistance in TiO₂ films and surfaces. Furthermore, the cause of the increase in performance may be due to the increase in the CB position of the CdSe:X QDs, which is higher than that of the TiO₂ conduction band. In addition, the energy level of metal ion appears in the band gap of CdSe QDs, which reduces the band gap energy of CdSe:X QDs. This result is evidenced by the shift and an increase in the intensity of the UV-Vis absorption spectra (Figure 2). From the above reasons, we can show an increase in the current density and decrease the resistance of the device.

(a)

(b)

4. Conclusions

The QDSSCs based on TiO₂/CdS/CdSe(3)Cu²⁺() with from 0% to 0.5% and TiO₂/CdS/CdSe(3)Mn²⁺() with from 0% to 40% were successfully fabricated by the SILAR method. The TiO₂/CdS/CdSe(3)Cu²⁺() cosensitized solar cells demonstrated better performance (4.3%) than the TiO₂/CdS/CdSe(3)Mn²⁺() (3.8%) and TiO₂/CdS(3)/CdSe(3) (1.96%). This result is a cause of the light harvesting for producing excitons, facility fast electron transfer at TiO2/CdS/CdSe:Mn²⁺(Cu²⁺) interfaces, and the reduced recombination in the QDSSCs as the concentration of Cu²⁺ (Mn²⁺) doped on the CdSe nanoparticles. In addition, the optical properties, the direct optical energy gap, and both the CB and VB levels of the compositional CdS, CdSe:Cu²⁺ and CdSe:Mn²⁺ were estimated by the theory of Tauc and discussed details. This theory is useful for us to understand the alignment energy structure of the compositions in electrodes, in particular, the CB and VB levels of CdS, CdSe:Cu²⁺, and CdSe:Mn²⁺ nanoparticles. As a result, there is a rise or drop of the CB and VB levels when Cu²⁺ (Mn²⁺) content was changed.

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest

The authors declare no competing interests.

Acknowledgments

The authors would like to thank University of Science, Viet Nam National University Ho Chi Minh City, Vietnam.

Supplementary Materials

Supplemental Figure 1: FESEM image at 100 nm (a, d), cross section at 1 μm (b, e), and EDX of CdSe:Mn²⁺ (20%) and CdSe:Cu²⁺ (0.3%) (c, f). (g, h) Raman spectroscopy of CdSe:X-QDSSCs. The morphology of preparing as-photoelectrodes with 20% of Mn²⁺ and 0.3% of Cu²⁺ could be obtained from FESEM. In addition, the compositions and structure of films could be investigated from EDX and Raman spectra. In general, these are the main data sets, which provided all information about the morphology, sizes, and thickness of a sandwich layer and structure of preparing as-photoelectrodes. Supplemental Figure 2: UV-Vis spectra of (a) CdSe(3)Mn²⁺ and (b) CdSe(3)Cu²⁺. ()2 vs. () curves of (c) CdSe(3)Mn²⁺ and (d) CdSe(3)Cu²⁺ QDs. This is the supplementary material which supports for us to determine the band gap of sample as getting the peak of UV-Vis spectra, in particular, calculate the conduction band and valence band of material. Supplemental Figure 3: photocurrent density-voltage (J-V) curves of (a) CdSe:Cu²⁺-QDSSCs and (b) CdSe:Mn²⁺-QDSSCs. The performance of the quantum dot-sensitized solar cells could be obtained from the photocurrent density-voltage curves. These results support the discussion from the electrochemical impedance spectra. Supplemental Figure 4: Nyquist curves of QDSSCs. (a) Mn²⁺ concentration changing from 0% to 40% and (b) Cu²⁺ concentration changing from 0% to 0.5%. The data set obtained from the electrochemical impedance spectra such as Nyquist curves, Bode phase. They are used to determine resistance dynamic, lifetime, and capacitances of the photoelectrodes to correlate with the shift of excited electrons from quantum dots to TiO2 nanoparticles, the diffusion of electrons. (Supplementary Materials)

References

S. Ruhle, M. Shalom, and A. Zaban, “Quantum-dot-sensitized solar cells,” ChemPhysChem, vol. 11, no. 11, pp. 2290–2304, 2010.
View at: Publisher Site | Google Scholar
C. Zhi and L. Dai, Eds., Flexible Energy Conversion and Storage Devices, John Wiley & Sons, 2018.
View at: Publisher Site
P. Yu, K. Zhu, A. G. Norman, S. Ferrere, A. J. Frank, and A. J. Nozik, “Nanocrystalline TiO₂ solar cells sensitized with InAs quantum dots,” The Journal of Physical Chemistry B, vol. 110, no. 50, pp. 25451–25454, 2006.
View at: Publisher Site | Google Scholar
Z. A. Peng and X. Peng, “Formation of high-quality CdTe, CdSe, and CdS nanocrystals using CdO as precursor,” Journal of the American Chemical Society, vol. 123, no. 1, pp. 183-184, 2001.
View at: Publisher Site | Google Scholar
M. C. Beard, “Multiple exciton generation in semiconductor quantum dots,” Journal of Physical Chemistry Letters, vol. 2, no. 11, pp. 1282–1288, 2011.
View at: Publisher Site | Google Scholar
E. H. Sargent, “Infrared quantum dots,” Advanced Materials, vol. 17, no. 5, pp. 515–522, 2005.
View at: Publisher Site | Google Scholar
J. Fang, J. Wu, X. Lu, Y. Shen, and Z. Lu, “Sensitization of nanocrystalline TiO₂ electrode with quantum sized CdSe and ZnTcPc molecules,” Chemical Physics Letters, vol. 270, no. 1-2, pp. 145–151, 1997.
View at: Publisher Site | Google Scholar
W. Lee, W.-C. Kwak, S. K. Min et al., “Spectral broadening in quantum dots-sensitized photoelectrochemical solar cells based on CdSe and Mg-doped CdSe nanocrystals,” Electrochemistry Communications, vol. 10, no. 11, pp. 1699–1702, 2008.
View at: Publisher Site | Google Scholar
J. Tao, Z. Sun, Y. Cheng et al., “Enhanced photoelectrochemical properties of nanocrystalline TiO₂ electrode by surface sensitization with Cu_xO quantum dots,” Scientific Reports, vol. 7, no. 1, p. 5291, 2017.
View at: Publisher Site | Google Scholar
L. M. Peter, D. J. Riley, E. J. Tull, and K. G. U. Wijayantha, “Photosensitization of nanocrystalline TiO₂ by self-assembled layers of CdS quantum dots,” Chemical Communications, no. 10, pp. 1030-1031, 2002.
View at: Publisher Site | Google Scholar
Z. L. Wang and W. Wu, “Nanotechnology-enabled energy harvesting for self-powered micro-/nanosystems,” Angewandte Chemie International Edition, vol. 51, no. 47, pp. 11700–11721, 2012.
View at: Publisher Site | Google Scholar
J. Chen, D. W. Zhao, J. L. Song et al., “Directly assembled CdSe quantum dots on TiO₂ in aqueous solution by adjusting pH value for quantum dot sensitized solar cells,” Electrochemistry Communications, vol. 11, no. 12, pp. 2265–2267, 2009.
View at: Publisher Site | Google Scholar
X.-Y. Yu, B.-X. Lei, D.-B. Kuang, and C.-Y. Su, “High performance and reduced charge recombination of CdSe/CdS quantum dot-sensitized solar cells,” Journal of Materials Chemistry, vol. 22, no. 24, pp. 12058–12063, 2012.
View at: Publisher Site | Google Scholar
S. W. Jung, J.-H. Kim, H. Kim, C.-J. Choi, and K.-S. Ahn, “ZnS overlayer on in situ chemical bath deposited CdS quantum dot-assembled TiO₂ films for quantum dot-sensitized solar cells,” Current Applied Physics, vol. 12, no. 6, pp. 1459–1464, 2012.
View at: Publisher Site | Google Scholar
M. Shalom, J. Albero, Z. Tachan, E. Martínez-Ferrero, A. Zaban, and E. Palomares, “Quantum dot-dye bilayer-sensitized solar cells: breaking the limits imposed by the low absorbance of dye monolayers,” The Journal of Physical Chemistry Letters, vol. 1, no. 7, article 1134, 1138 pages, 2010.
View at: Publisher Site | Google Scholar
T. Zewdu, J. N. Clifford, J. P. Hernández, and E. Palomares, “Photo-induced charge transfer dynamics in efficient TiO₂/CdS/CdSe sensitized solar cells,” Energy & Environmental Science, vol. 4, no. 11, p. 4633, 2011.
View at: Publisher Site | Google Scholar
J. Jiao, Z.-J. Zhou, W.-H. Zhou, and S.-X. Wu, “CdS and PbS quantum dots co-sensitized TiO₂ nanorod arrays with improved performance for solar cells application,” Materials Science in Semiconductor Processing, vol. 16, no. 2, pp. 435–440, 2013.
View at: Publisher Site | Google Scholar
Y.-J. Shen and Y.-L. Lee, “Assembly of CdS quantum dots onto mesoscopic TiO₂ films for quantum dot-sensitized solar cell application,” Nanotechnology, vol. 19, no. 4, article 045602, 2008.
View at: Publisher Site | Google Scholar
W. W. Yu, L. Qu, W. Guo, and X. Peng, “Experimental determination of the extinction coefficient of CdTe, CdSe, and CdS nanocrystals,” Chemistry of Materials, vol. 15, no. 14, pp. 2854–2860, 2003.
View at: Publisher Site | Google Scholar
F. Zhuge, X. Li, X. Gao, X. Gan, and F. Zhou, “Synthesis of stable amorphous Cu₂S thin film by successive ion layer adsorption and reaction method,” Materials Letters, vol. 63, no. 8, pp. 652–654, 2009.
View at: Publisher Site | Google Scholar
S.-Q. Fan, R.-J. Cao, Y.-X. Xi, M. Gao, M.-D. Wang, and D.-H. Kima, “CdSe quantum dots as co-sensitizers of organic dyes in solar cells for red-shifted light harvesting,” Optoelectronics and Advanced Materials – Rapid Communications, vol. 3, no. 10, pp. 1027–1033, 2009.
View at: Google Scholar
B. Fang, M. Kim, S. Q. Fan et al., “Facile synthesis of open mesoporous carbon nanofibers with tailored nanostructure as a highly efficient counter electrode in CdSe quantum-dot-sensitized solar cells,” Journal of Materials Chemistry, vol. 21, no. 24, pp. 8742–8748, 2011.
View at: Publisher Site | Google Scholar
G. Chmid, Nanoparticles: From Theory to Application, Wiley-VCH, 2014.
V. S. Raut, C. D. Lokhande, and V. V. Killedar, “Studies on effect of pH on structural, optical and morphological properties of chemisynthesized CdSe grains,” International Journal of Engineering, vol. 10, no. 1, p. 2017, 2017.
View at: Google Scholar
S. Giménez, I. Mora-Seró, L. Macor et al., “Improving the performance of colloidal quantum-dot-sensitized solar cells,” Nanotechnology, vol. 20, no. 29, article 295204, 2009.
View at: Publisher Site | Google Scholar
V. Gonzalez-Pedro, X. Xu, I. Mora-Sero, and J. Bisquert, “Modeling high-efficiency quantum dot sensitized solar cells,” ACS Nano, vol. 4, no. 10, pp. 5783–5790, 2010.
View at: Publisher Site | Google Scholar
M. Gratzel, “Photoelectrochemical cells,” Nature, vol. 414, no. 6861, pp. 338–344, 2001.
View at: Publisher Site | Google Scholar
M. Gratzel, “Dye-sensitized solar cells,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 4, no. 2, pp. 145–153, 2003.
View at: Publisher Site | Google Scholar
K. Veerathangam, M. S. Pandian, and P. Ramasamy, “Photovoltaic performance of Ag-doped CdS quantum dots for solar cell application,” Materials Research Bulletin, vol. 94, pp. 371–377, 2017.
View at: Publisher Site | Google Scholar
D. H. Phuc and H. T. Tung, “The effect of thickness on the performance of CdSe: Cu²⁺—quantum dot-sensitized solar cells,” Applied Physics A, vol. 124, no. 11, p. 731, 2018.
View at: Publisher Site | Google Scholar
J. Y. Kim, S. B. Choi, J. H. Noh et al., “Synthesis of CdSe-TiO₂ nanocomposites and their applications to TiO₂ sensitized solar cells,” Langmuir, vol. 25, no. 9, pp. 5348–5351, 2009.
View at: Publisher Site | Google Scholar
Y.-L. Xie, “Enhanced photovoltaic performance of hybrid solar cell using highly oriented CdS/CdSe-modified TiO₂ nanorods,” Electrochimica Acta, vol. 105, pp. 137–141, 2013.
View at: Publisher Site | Google Scholar
A. Sharma, N. Mehta, and A. Kumar, “Dielectric relaxation in Se_80−xTe₂₀Sn_x chalcogenide glasses,” Journal of Materials Science, vol. 46, no. 13, pp. 4509–4516, 2011.
View at: Publisher Site | Google Scholar
P. Mandal, S. S. Talwar, S. S. Major, and R. S. Srinivasa, “Orange-red luminescence from Cu doped CdS nanophosphor prepared using mixed Langmuir–Blodgett multilayers,” Journal of Chemical Physics, vol. 128, no. 11, article 114703, 2008.
View at: Publisher Site | Google Scholar
S. B. Singh, M. V. Limaye, N. P. Lalla, and S. K. Kulkarni, “Copper-ion-induced photoluminescence tuning in CdSe nanoparticles,” Journal of Luminescence, vol. 128, no. 12, pp. 1909–1912, 2008.
View at: Publisher Site | Google Scholar
B. B. Srivastava, S. Jana, and N. Pradhan, “Doping Cu in semiconductor nanocrystals: some old and some new physical insights,” Journal of the American Chemical Society, vol. 133, no. 4, pp. 1007–1015, 2011.
View at: Publisher Site | Google Scholar
M. P. A. Muthalif, Y. S. Lee, C. D. Sunesh, H. J. Kim, and Y. Choe, “Enhanced photovoltaic performance of quantum dot-sensitized solar cells with a progressive reduction of recombination using Cu-doped CdS quantum dots,” Applied Surface Science, vol. 396, pp. 582–589, 2017.
View at: Publisher Site | Google Scholar
N. S. Karan, D. D. Sarma, R. M. Kadam, and N. Pradhan, “Doping transition metal (Mn or Cu) ions in semiconductor nanocrystals,” Journal of Physical Chemistry Letters, vol. 1, no. 19, pp. 2863–2866, 2010.
View at: Publisher Site | Google Scholar
K. Veerathangam, M. Senthil Pandian, and P. Ramasamy, “Photovoltaic performance of Pb-doped CdS quantum dots for solar cell application,” Materials Letters, vol. 220, pp. 74–77, 2018.
View at: Publisher Site | Google Scholar
O. Amiri, M. Salavati-Niasari, and M. Farangi, “Enhancement of dye-sensitized solar cells performance by core shell Ag@organic (organic=2-nitroaniline, PVA, 4-choloroaniline and PVP): effects of shell type on photocurrent,” Electrochimica Acta, vol. 153, pp. 90–96, 2015.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2019 Dang Huu Phuc and Ha Thanh Tung. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

1853

Downloads

996

Citations

International Journal of Photoenergy

Advanced Nanomaterials and Nanotechnologies for Solar Energy

Band Tunable CdSe Quantum Dot-Doped Metals for Quantum Dot-Sensitized Solar Cell Application

Abstract

1. Introduction

2. Experiment

2.1. TiO2 and TiO2/CdS Films Were Prepared As Follows Ref [29]

2.2. A TiO2/CdS/CdSe:Mn2+ Film

2.3. A TiO2/CdS/CdSe:Cu2+ Film

2.4. Characterization

3. Results and Discussion

4. Conclusions

Data Availability

Conflicts of Interest

Acknowledgments

Supplementary Materials

References

Copyright

2.1. TiO₂ and TiO₂/CdS Films Were Prepared As Follows Ref [29]

2.2. A TiO₂/CdS/CdSe:Mn²⁺ Film

2.3. A TiO₂/CdS/CdSe:Cu²⁺ Film