In situ growth of CuInS2 nanocrystals on nanoporous TiO2 film for constructing inorganic/organic heterojunction solar cells
© Chen et al.; licensee Springer. 2013
Received: 17 June 2013
Accepted: 8 August 2013
Published: 16 August 2013
Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2( CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as ‘petals’ with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure.
KeywordsCuInS2 film In situ growth TiO2 P3HT Heterojunction solar cells PACS 81.15.-z 84.60.Jt 73.40.Lq
The quest and demand for clean and economical energy sources have increased interest in the development of various solar cells, such as Si solar cells, Cu(In,Ga)(S,Se)2 film solar cells[3–6], organic solar cells, and dye-sensitized solar cells (DSSCs)[8–12]. Among these solar cells, DSSCs have been currently attracting widespread scientific and technological interest due to their low cost and high efficiency[8–12]. The typical working principle of DSSCs is based on ultrafast electron injection from a photoexcited dye into the conduction band of TiO2 and subsequent dye regeneration and hole transportation to the counter electrode. The power conversion efficiency of DSSCs with organic solvent-based electrolyte has been reported to exceed 11%[9, 13, 14]. However, DSSCs still suffer from some problems, such as high cost of Ru-based dyes, leakage and/or evaporation from organic solvent-based electrolyte.
For reducing the cost, the use of inorganic semiconductor nanocrystals instead of Ru-based dyes in DSSCs has attracted an enormous interest[15–18]. Semiconductor nanocrystals as the sensitizers have many fascinating advantages, such as high extinction coefficients, large intrinsic dipole moments, and the tuned bandgap. In particular, semiconductor quantum dots have capability of producing multiple electron/hole pairs with a single photon through the impact ionization effect. For depositing semiconductor nanocrystals on TiO2 films, two typical approaches have been developed. The first and most common route is the in situ synthesis of the nanocrystals on TiO2 film, for example, by chemical bath deposition or by successive ionic layer adsorption and reaction (SILAR). This method provides high surface coverage, but the lack of capping agents leads to a broad size distribution and a higher density of surface defects of nanocrystals, which deteriorates solar cell performance. The second route is the assembly of already-synthesized nanocrystals to TiO2 substrates by direct adsorption or linker-assisted adsorption. This ex situ approach could achieve better control over the sizes and electronic properties of nanocrystals but suffers from low surface coverage and poor electronic coupling. Up to now, many different semiconductor nanocrystals as the sensitizers have been investigated, including CdSe[17, 22, 25], CdS[21, 26], and PbS[27–29]. Unfortunately, these metal chalcogenide semiconductors are easily oxidized when exposed to light, and this unfavorable situation is even more detrimental when the metal sulfide is in contact with a liquid electrolyte containing sulfur. It is well known that the choice of semiconductors and the method of their deposition play a paramount role in affecting cell efficiency. Therefore, it is still necessary to develop new materials and deposition methods for improving DSSCs with semiconductors as the sensitizers.
On the other hand, for avoiding the sealing problem in DSSCs, many attempts have been made to substitute liquid electrolytes with quasi-solid electrolytes or solid-state hole transporting material (HTM). Similarly, when semiconductor nanocrystals are used as the sensitizers, some HTMs including poly(3-hexylthiophene) (P3HT) have been developed, resulting in the construction of all-solid-state inorganic/organic heterojunction solar cells (HSCs)[32–36], which possesses the advantages of both DSSCs and traditional organic solar cells. In particular, the efficiency of HSCs with the structure of TiO2/Sb2S3/P3HT has reached 5%, which is very close to the efficiencies reported for solid DSSCs using Ru-based molecular dyes. In addition, Sb2S3 nanocrystals are non-toxic compared with Cd/Pb-based semiconductors. These facts show the great potentiality of all-solid HSCs, which also encourages to further achieve other kind of robust, efficient, and cheap HSCs without toxic component.
Copper indium disulfide (CuInS2, abbreviated as CIS) has a small direct bandgap of 1.5 eV that matches well the solar spectrum, a large absorption coefficient (α = 5 × 105 cm−1), and low toxicity. It has been regarded to be a promising light-absorbing material for film solar cells. As semiconductor sensitizers in DSSCs, CIS nanocrystals have been prepared by different methods and then were coated/adsorbed on TiO2 film to construct DSSCs with liquid electrolyte[24, 37, 38]. In addition, the in situ growth of CIS on TiO2 film has also been realized, by electrodeposition, spin-coating/anneal, and SILAR method, to construct DSSCs with liquid electrolyte. However, there is little report on solvothermal growth of CIS nanocrystals on TiO2 film for the construction of all-solid HSCs. In this paper, we report a facile one-step solvothermal route for the in situ growth CIS nanocrystals on nanoporous TiO2 film. The effects of reagent concentration on the surface morphology of CIS have been investigated. The all-solid HSC with the structure of FTO/compact-TiO2 /nanoporous-TiO2/CIS/P3HT/PEDOT:PSS/Au is fabricated, and it exhibits a relatively high conversion efficiency of 1.4%.
All of the chemicals were commercially available and were used without further purification. Titanium butoxide, petroleum ether, TiCl4, CuSO4 · 5H2O, InCl3 · 4H2O, thioacetamide, ethanol, methanol, and 1,2-dichlorobenzene were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). TiO2 (P25) was obtained from Degussa. Transparent conductive glass (F:SnO2, FTO) was purchased from Wuhan Geao Instruments Science & Technology Co., Ltd (Wuhan, Hubei, China). P3HT was bought from Guanghe Electronic Materials Co., Ltd. (Henan, China). The poly(3-4-ethylenedioxythiophene) doped with poly(4-stylenesulfonate) (PEDOT:PSS) solution (solvent, H2O; weight percentage, 1.3%) was obtained from Aldrich (St. Louis, MO, USA).
Preparation of compact and nanoporous TiO2 film
A part of FTO glass was chemically etched away in order to prevent direct contact between the two electrodes. A compact (about 100-nm thick) TiO2 layer was first deposited onto the FTO glass as follow. FTO glass was dipped into the mixture of titanium butoxide and petroleum ether (2:98 V/V), taken out carefully, hydrolyzed in air for 30 min, and sintered in oven for 30 min at 450°C.
Then, nanoporous TiO2 films were prepared by the doctor-blading technique with TiO2 (P25) colloidal dispersion and subsequently sintered at 450°C for 30 min, according to a previous study. This film was soaked into a TiCl4 (20 mM in water) solution for 12 h. It was then washed with deionized water and ethanol, dried with air, and sintered again at 450°C for 30 min.
In situ solvothermal growth of CuInS2nanocrystals
CIS layer was in situ grown on nanoporous TiO2 films by a solvothermal process. In a typical process, thioacetamide (0.24 mmol, 0.02 M) was added into a 12 mL ethanol solution containing InCl3 · 4H2O (0.01 M) and CuSO4 · 5H2O (0.01 M) under magnetic stirring, until a clear solution was formed. The resulting solution was transferred into a Teflon-lined stainless steel autoclave with 30-mL capacity. Subsequently, FTO/compact-TiO2/nanoporous-TiO2 film as the substrate was vertically immersed into the solution. Lastly, the autoclave was kept in a fan-forced oven at 160°C for 12 h. After air-cooling to room temperature, CIS film on non-conductive glass side was scraped off, while CIS film on nanoporous TiO2 film side was washed with deionized water and absolute ethanol successively, and dried in air. For comparison, the effects of InCl3 · 4H2O concentrations (0.01, 0.03, 0.1 M) on the morphologies CIS layer were investigated. The concentration ratio of InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide was maintained constant (1:1:2) for all the cases.
Fabrication of all-solid HSC
The P3HT solution (10 mg/mL in 1,2-dichlorobenzene) was spin-coated onto TiO2/CIS with 3,000 rpm for 60 s. Then, in order to improve the contact between P3HT and gold, a PEDOT:PSS solution diluted with two volumes of methanol was introduced onto TiO2/CIS/P3HT layer by spin-coating at 2,000 rpm for 30 s. In order to form a hybrid heterojunction, the TiO2/CIS/P3HT/PEDOT:PSS layer was then annealed at 90°C for 30 min in a vacuum oven. Gold layer as the back contact was prepared by magnetron sputtering with a metal mask, giving an active area of 16 mm2 for each device. The resulting HSC has a structure of FTO/compact-TiO2/nanoporous-TiO2/CIS/P3HT/PEDOT:PSS/Au.
Characterization and photoelectrical measurements
The sizes and morphologies of the sample were investigated by field emission scanning electron microscopy (FE-SEM; S-4800, Hitachi, Chiyoda-ku, Japan). During SEM measurement, energy dispersive spectroscopy (EDS; Quantax 400, Bruker AXS, Inc., Madison, WI, USA) line scan was also performed to locate and determine the distribution of different layer in the composite film. The X-ray diffraction (XRD; D/max-g B, Rigaku, Shibuya-ku, Japan) measurement was carried out using a Cu Kα radiation source (λ = 1.5418 Å). An ultraviolet/visible (UV-vis) spectrophotometer (U-3010 spectrophotometer, Hitachi, Chiyoda-ku, Japan) was used to carry out the optical measurements. The photocurrent density/voltage curves of HSC was measured under illumination (100 mW cm−2) using a computerized Keithley Model 2400 Source Meter unit (Keithley Instruments Inc., Cleveland, OH, USA) and a 300-W xenon lamp (Newport 69911, Newport-Oriel Instruments, Stratford, CT, USA) serving as the light source.
Results and discussion
The fourth step was to in turn deposit P3HT and PEDOT:PSS layer on FTO/compact-TiO2/nanoporous-TiO2/CIS film by the spin-coating process (Figure 1 (step D)). After the coating of P3HT, the photoabsorption of the film increases obviously in the range of 400 to 700 nm, as shown in Figure 8 (line B), since P3HT solution exhibits a wide and strong absorption with peak at about 445 nm. This fact also indicates the efficient deposition of P3HT in/on TiO2/CIS film. It should be noted that there are plenty of macro-pores among superstructures, nanopores inside CIS flower-shaped superstructures, and nanopores in TiO2 film due to the insufficient filling. The hierarchical combination of smaller nanopores and larger macro-pores can be considered as transport paths. It can be expected that P3HT solution can easily enter the deep layer of FTO/compact-TiO2/nanoporous-TiO2/CIS film through the transport paths, when they are coated onto its surface during the spin-coating process. This should lead to better effects of wetting and pore-filling and thus better interfacial contact among P3HT, CIS, and TiO2, probably resulting in more efficient separation of photoinduced electron/hole pairs and thus higher photocurrent.
In summary, an in situ growth of CIS nanocrystals has been demonstrated by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. When InCl3 concentration is 0.1 M, there is a CIS layer on the top of TiO2 film, and the pores of TiO2 film have been filled by CIS nanoparticles. An HSC with the structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement can be expected by optimizing CIS layer and the cell structure.
This work was financially supported by the National Natural Science Foundation of China (grant nos. 21107013, 21171035, and 51272299), Specialized Research Fund for the Doctoral Program of Higher Education (grant no. 20110075120012), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, projects of the Shanghai Committee of Science and Technology (grant nos. 10JC1400100, 13JC1400300), Innovation Program of Shanghai Municipal Education Commission (grant no. 13ZZ053), the Fundamental Research Funds for the Central Universities, the Shanghai Leading Academic Discipline Project (grant no. B603), and the Program of Introducing Talents of Discipline to Universities (grant no. 111-2-04).
- Gratzel M: Photoelectrochemical cells. Nature 2001, 414: 338–344. 10.1038/35104607View ArticleGoogle Scholar
- Peng KQ, Wang X, Li L, Wu XL, Lee ST: High-performance silicon nanohole solar cells. J Am Chem Soc 2010, 132: 6872–6873. 10.1021/ja910082yView ArticleGoogle Scholar
- Jackson P, Hariskos D, Lotter E, Paetel S, Wuerz R, Menner R, Wischmann W, Powalla M: New world record efficiency for Cu (In, Ga)Se2 thin-film solar cells beyond 20%. Prog Photovolt Res Appl 2011, 19: 894–897. 10.1002/pip.1078View ArticleGoogle Scholar
- Tang M, Tian Q, Hu X, Peng Y, Xue Y, Chen Z, Yang J, Xu X, Hu J: In situ preparation of CuInS2 films on a flexible copper foil and their application in thin film solar cells. Cryst Eng Comm 2012, 14: 1825–1832. 10.1039/c1ce05756aView ArticleGoogle Scholar
- Zhang L, Song L, Tian Q, Kuang X, Hu J, Liu J, Yang J, Chen Z: Flexible fiber-shaped CuInSe2 solar cells with single-wire-structure: design, construction and performance. Nano Energy 2012, 1: 769–776. 10.1016/j.nanoen.2012.07.022View ArticleGoogle Scholar
- Reddy VR, Wu J, Manasreh MO: Colloidal Cu(In x Ga1−x)Se2 nanocrystals for all-inorganic nano-heterojunction solar cells. Mater Lett 2013, 92: 296–299.View ArticleGoogle Scholar
- Lee K, Kim JY, Coates NE, Moses D, Nguyen TQ, Dante M, Heeger AJ: Efficient tandem polymer solar cells fabricated by all-solution processing. Science 2007, 317: 222–225. 10.1126/science.1141711View ArticleGoogle Scholar
- Oregan B, Gratzel M: A low-cost, high-efficiency solar-cell based on dye-sensitized colloidal TiO2 films. Nature 1991, 353: 737–740. 10.1038/353737a0View ArticleGoogle Scholar
- Gratzel M: Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells. J Photoch Photobio A 2004, 164: 3–14. 10.1016/j.jphotochem.2004.02.023View ArticleGoogle Scholar
- Chen ZG, Li FY, Huang CH: Organic d-pi-a dyes for dye-sensitized solar cell. Curr Org Chem 2007, 11: 1241–1258. 10.2174/138527207781696008View ArticleGoogle Scholar
- Chen ZG, Li FY, Yang H, Yi T, Huang CH: A thermostable and long-term-stable ionic-liquid-based gel electrolyte for efficient dye-sensitized solar cells. Chem Phys Chem 2007, 8: 1293–1297. 10.1002/cphc.200700116Google Scholar
- Hagfeldt A, Boschloo G, Sun L, Kloo L, Pettersson H: Dye-sensitized solar cells. Chem Rev 2010, 110: 6595–6663. 10.1021/cr900356pView ArticleGoogle Scholar
- Chen C-Y, Wang M, Li J-Y, Pootrakulchote N, Alibabaei L, C-h N-l, Decoppet J-D, Tsai J-H, Graetzel C, Wu C-G, Zakeeruddin SM, Grätzel M: Highly efficient light-harvesting ruthenium sensitizer for thin-film dye-sensitized solar cells. ACS Nano 2009, 3: 3103–3109. 10.1021/nn900756sView ArticleGoogle Scholar
- Yella A, Lee H-W, Tsao HN, Yi C, Chandiran AK, Nazeeruddin MK, Diau EW-G, Yeh C-Y, Zakeeruddin SM, Graetzel M: Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency. Science 2011, 334: 629–634. 10.1126/science.1209688View ArticleGoogle Scholar
- Robel I, Subramanian V, Kuno M, Kamat PV: Quantum dot solar cells. Harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films. J Am Chem Soc 2006, 128: 2385–2393. 10.1021/ja056494nView ArticleGoogle Scholar
- Yun JH, Ng YH, Huang SJ, Conibeer G, Amal R: Wrapping the walls of n-TiO2 nanotubes with p-CuInS2 nanoparticles using pulsed-electrodeposition for improved heterojunction photoelectrodes. Chem Commun 2011, 47: 11288–11290. 10.1039/c1cc13738gView ArticleGoogle Scholar
- Choi H, Santra PK, Kamat PV: Synchronized energy and electron transfer processes in covalently linked CdSe-squaraine dye-TiO light harvesting assembly. ACS Nano 2012, 6: 5718–5726. 10.1021/nn301982eView ArticleGoogle Scholar
- Santra PK, Kamat PV: Tandem-layered quantum dot solar cells: tuning the photovoltaic response with luminescent ternary cadmium chalcogenides. J Am Chem Soc 2013, 135: 877–885. 10.1021/ja310737mView ArticleGoogle Scholar
- Alivisatos AP: Semiconductor clusters, nanocrystals, and quantum dots. Science 1996, 271: 933–937. 10.1126/science.271.5251.933View ArticleGoogle Scholar
- Nozik AJ: Exciton multiplication and relaxation dynamics in quantum dots: applications to ultrahigh-efficiency solar photon conversion. Inorg Chem 2005, 44: 6893–6899. 10.1021/ic0508425View ArticleGoogle Scholar
- Yan KY, Chen W, Yang SH: Significantly enhanced open circuit voltage and fill factor of quantum dot sensitized solar cells by linker seeding chemical bath deposition. J Phys Chem C 2013, 117: 92–99. 10.1021/jp3094319View ArticleGoogle Scholar
- Lee H, Wang MK, Chen P, Gamelin DR, Zakeeruddin SM, Gratzel M, Nazeeruddin MK: Efficient CdSe quantum dot-sensitized solar cells prepared by an improved successive ionic layer adsorption and reaction process. Nano Lett 2009, 9: 4221–4227. 10.1021/nl902438dView ArticleGoogle Scholar
- Mora-Sero I, Gimenez S, Fabregat-Santiago F, Gomez R, Shen Q, Toyoda T, Bisquert J: Recombination in quantum dot sensitized solar cells. Accounts Chem Res 2009, 42: 1848–1857. 10.1021/ar900134dView ArticleGoogle Scholar
- Li TL, Teng HS: Solution synthesis of high-quality CuInS2 quantum dots as sensitizers for TiO2 photoelectrodes. J Mater Chem 2010, 20: 3656–3664. 10.1039/b927279hView ArticleGoogle Scholar
- Yu Y, Kamat PV, Kuno M: A CdSe nanowire/quantum dot hybrid architecture for improving solar cell performance. Adv Funct Mater 2010, 20: 1464–1472. 10.1002/adfm.200902372View ArticleGoogle Scholar
- Chen C, Ali G, Yoo SH, Kum JM, Cho SO: Improved conversion efficiency of CdS quantum dot-sensitized TiO2 nanotube-arrays using CuInS2 as a co-sensitizer and an energy barrier layer. J Mater Chem 2011, 21: 16430–16435. 10.1039/c1jm13616jView ArticleGoogle Scholar
- Etgar L, Park J, Barolo C, Nazeeruddin MK, Viscardi G, Graetzel M: Design and development of novel linker for PbS quantum dots/TiO2 mesoscopic solar cell. ACS Appl Mater Inter 2011, 3: 3264–3267. 10.1021/am200811cView ArticleGoogle Scholar
- Benehkohal NP, Gonzalez-Pedro V, Boix PP, Chavhan S, Tena-Zaera R, Demopoulos GP, Mora-Sero I: Colloidal PbS and PbSeS quantum dot sensitized solar cells prepared by electrophoretic deposition. J Phys Chem C 2012, 116: 16391–16397. 10.1021/jp3056009View ArticleGoogle Scholar
- Etgar L, Moehl T, Gabriel S, Hickey SG, Eychmueller A, Graetzel M: Light energy conversion by mesoscopic PbS quantum dots/TiO2 heterojunction solar cells. ACS Nano 2012, 6: 3092–3099. 10.1021/nn2048153View ArticleGoogle Scholar
- Chen ZG, Yang H, Li XH, Li FY, Yi T, Huang CH: Thermostable succinonitrile-based gel electrolyte for efficient, long-life dye-sensitized solar cells. J Mater Chem 2007, 17: 1602–1607. 10.1039/b615915jView ArticleGoogle Scholar
- Bach U, Lupo D, Comte P, Moser JE, Weissortel F, Salbeck J, Spreitzer H, Gratzel M: Solid-state dye-sensitized mesoporous TiO2 solar cells with high photon-to-electron conversion efficiencies. Nature 1998, 395: 583–585. 10.1038/26936View ArticleGoogle Scholar
- Chang JA, Rhee JH, Im SH, Lee YH, Kim H-J, Seok SI, Nazeeruddin MK, Gratzel M: High-performance nanostructured inorganic–organic heterojunction solar cells. Nano Lett 2010, 10: 2609–2612. 10.1021/nl101322hView ArticleGoogle Scholar
- Balis N, Dracopoulos V, Stathatos E, Boukos N, Lianos P: A solid-state hybrid solar cell made of nc-TiO2, CdS quantum dots, and P3HT with 2-amino-1-methylbenzimidazole as an interface modifier. J Phys Chem C 2011, 115: 10911–10916.View ArticleGoogle Scholar
- Qian J, Liu Q-S, Li G, Jiang K-J, Yang L-M, Song Y: P3HT as hole transport material and assistant light absorber in CdS quantum dots-sensitized solid-state solar cells. Chem Commun 2011, 47: 6461–6463. 10.1039/c1cc11595bView ArticleGoogle Scholar
- Liu CP, Wang HE, Ng TW, Chen ZH, Zhang WF, Yan C, Tang YB, Bello I, Martinu L, Zhang WJ, Jha SK: Hybrid photovoltaic cells based on ZnO/Sb2S3/P3HT heterojunctions. Phys Status Solidi B 2012, 249: 627–633. 10.1002/pssb.201147393View ArticleGoogle Scholar
- Heo JH, Im SH, Kim H-J, Boix PP, Lee SJ, Seok SI, Mora-Sero I, Bisquert J: Sb2S3-sensitized photoelectrochemical cells: open circuit voltage enhancement through the introduction of poly-3-hexylthiophene interlayer. J Phys Chem C 2012, 116: 20717–20721. 10.1021/jp305150sView ArticleGoogle Scholar
- Li TL, Lee YL, Teng H: High-performance quantum dot-sensitized solar cells based on sensitization with CuInS2 quantum dots/CdS heterostructure. Energ Environ Sci 2012, 5: 5315–5324. 10.1039/c1ee02253aView ArticleGoogle Scholar
- Santra PK, Nair PV, Thomas KG, Kamat PV: CuInS2-sensitized quantum dot solar cell. Electrophoretic deposition, excited-state dynamics, and photovoltaic performance. J Phys Chem Lett 2013, 4: 722–729. 10.1021/jz400181mView ArticleGoogle Scholar
- Zhou ZJ, Fan JQ, Wang X, Sun WZ, Zhou WH, Du ZL, Wu SX: Solution fabrication and photoelectrical properties of CuInS2 nanocrystals on TiO2 nanorod array. ACS Appl Mater Inter 2011, 3: 2189–2194. 10.1021/am200500kView ArticleGoogle Scholar
- Zhou ZJ, Yuan SJ, Fan JQ, Hou ZL, Zhou WH, Du ZL, Wu SX: CuInS2 quantum dot-sensitized TiO2 nanorod array photoelectrodes: synthesis and performance optimization. Nanoscale Res Lett 2012, 7: 652. 10.1186/1556-276X-7-652View ArticleGoogle Scholar
- Chen ZG, Tang YW, Yang H, Xia YY, Li FY, Yi T, Huang CH: Nanocrystalline TiO2 film with textural channels: exhibiting enhanced performance in quasi-solid/solid-state dye-sensitized solar cells. J Power Sources 2007, 171: 990–998. 10.1016/j.jpowsour.2007.07.007View ArticleGoogle Scholar
- Nazeeruddin MK, Kay A, Rodicio I, Humphrybaker R, Muller E, Liska P, Vlachopoulos N, Gratzel M: Conversion of light to electricity by cis-x2bis(2,2′-bipyridyl-4,4′-dicarboxylate)ruthenium(ii) charge-transfer sensitizers (x = cl-, br-, i-, cn-, and scn-) on nanocrystalline TiO2 electrodes. J Am Chem Soc 1993, 115: 6382–6390. 10.1021/ja00067a063View ArticleGoogle Scholar
- Peng Y, Song G, Hu X, He G, Chen Z, Xu X, Hu J: In situ synthesis of P3HT-capped CdSe superstructures and their application in solar cells. Nanoscale Res Lett 2013, 8: 106. 10.1186/1556-276X-8-106View ArticleGoogle Scholar
- Chuang C-H, Lin Y-Y, Tseng Y-H, Chu T-H, Lin C-C, Su W-F, Chen C-W: Nanoscale morphology control of polymer/TiO2 nanocrystal hybrids: photophysics, charge generation, charge transport, and photovoltaic properties. J Phys Chem C 2010, 114: 18717–18724. 10.1021/jp1075516View ArticleGoogle Scholar
- Gerein NJ, Fleischauer MD, Brett MJ: Effect of TiO2 film porosity and thermal processing on TiO2-P3HT hybrid materials and photovoltaic device performance. Sol Energ Mat Sol Cells 2010, 94: 2343–2350. 10.1016/j.solmat.2010.08.010View ArticleGoogle Scholar
- Zeng T-W, Ho C-C, Tu Y-C, Tu G-Y, Wang L-Y, Su W-F: Correlating interface heterostructure, charge recombination, and device efficiency of poly(3-hexyl thiophene)/TiO2 nanorod solar cell. Langmuir 2011, 27: 15255–15260. 10.1021/la203533uView ArticleGoogle Scholar
- Tu Y-C, Lin J-F, Lin W-C, Liu C-P, Shyue J-J, Su W-F: Improving the electron mobility of TiO2 nanorods for enhanced efficiency of a polymer-nanoparticle solar cell. Cryst Eng Comm 2012, 14: 4772–4776. 10.1039/c2ce25489aView ArticleGoogle Scholar
- Im SH, Kim HJ, Rhee JH, Lim CS, Sang SI: Performance improvement of Sb2S3-sensitized solar cell by introducing hole buffer layer in cobalt complex electrolyte. Energ Environ Sci 2011, 4: 2799–2802. 10.1039/c0ee00741bView ArticleGoogle Scholar
- Cardoso JC, Grimes CA, Feng XJ, Zhang XY, Komarneni S, Zanoni MVB, Bao NZ: Fabrication of coaxial TiO2/Sb2S3 nanowire hybrids for efficient nanostructured organic-inorganic thin film photovoltaics. Chem Commun 2012, 48: 2818–2820. 10.1039/c2cc17573hView ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.