本文へスキップ

ホーム | 研究内容 | 研究業績 | メンバー | 写真 | アクセス・お問い合わせ | リンク 



                  
イメージ写真1 イメージ写真1 イメージ写真1 イメージ写真1
NEWS / 研究ハイライト   
研究ハイライト
    
イメージ写真2
Fig. (a, b) A schematic illustration
of the ZnO@TiO2/PbS solar cells;
(c, d) photographs of the PbS CQDSCs
before and after the deposition of the Au contacts;
High reduction of interfacial charge recombination in colloidal quantum dot solar cells by metal oxide surface passivation
Bulk heterojunction (BHJ) solar cells based on colloidal QDs and metal oxide nanowires (NWs) possess unique and outstanding advantages in enhancing light harvesting and charge collection in comparison to planar architectures. However, the high surface area of the NW structure often brings about a large amount of recombination (especially interfacial recombination) and limits the open-circuit voltage in BHJ solar cells. This problem is solved here by passivating the surface of the metal oxide component in PbS colloidal quantum dot solar cells (CQDSCs). [See more]

J. Chang, Y. Kuga, I. Mora-Seró, T. Toyoda, Y. Ogomi, S. Hayase, J. Bisquert and Q. Shen
イメージ写真2
Fig. Schematic diagram of the PbS/ZnS sensitized solar cells. The solid arrows indicate the excitation of PbS QDs and the injection/transfer of photoexcited charges. The dotted arrows indicate the charge recombination at the TiO2/QD/electrolyte interfaces.
Uncovering the charge transfer and recombination mechanism in ZnS-coated PbS quantum dot sensitized solar cells
In this work, the charge transfer and recombination mechanism is uncovered for the PbS/ZnS quantum dot sensitized solar cells (QDSSCs) based on nanoporous TiO2 electrodes. PbS quantum dots (QDs) were in-situ grown on TiO2 nanoparticles through the successive ionic absorption and reaction (SILAR) method, followed by the surface passivation of ZnS for the sensitized electrodes. It was observed that the ZnS coating cycles play a significant role in determining the photovoltaic parameters. [See more]

J. Chang, T. Oshima, S. Hachiy, K. Sato, T. Toyoda, K. Katayama, S. Hayase, Q. Shen





イメージ写真2Fig. Dependence of normalized TA responses of CH3NH3PbClI2/ TiO2 on pump light intensity. The pump light wavelength is 470 nm and the probe light wavelength is 775 nm.







Charge transfer and recombination at the metaloxide/CH3NH 3PbClI2/spiro-OMeTAD interfaces: Uncovering the detailed mechanism behind high efficiency solar cells
In recent years, organometal halide perovskite-based solid-state hybrid solar cells have attracted unexpected increasing interest because of their high efficiency (the record power conversion efficiency has been reported to be over 15%) and low fabrication cost. It has been accepted that the high efficiency was mainly attributed to the strong optical absorption (absorption coefficient: 15 000 cm1 at 550 nm) over a broader range (up to 800 nm) and the long lifetimes of photoexcited charge carriers (in the order of 10 ns – a few 100 ns) of the perovskite absorbers. [See more]

Q. Shen, Y. Ogomi, J. Chang, S. Tsukamoto, K. Kukihara,
T. Oshima, N. Osada, K. Yoshino, K. Katayama, T. Toyoda S. Hayase
イメージ写真2
Fig. AFM images of CdSe QDs adsorbed on (001),








Effect of TiO2 Crystal Orientation on the Adsorption of CdSe Quantum Dots for Photosensitization Studied by the Photoacoustic
and Photoelectron Yield Methods
We describe the adsorption and growth of CdSe quantum dots (QDs) on single crystals of rutile TiO2 with different crystal orientations. We used atomic force microscopy (AFM) to characterize the morphology of the QDs and photoacoustic (PA) spectroscopy to measure the optical absorption. Photoelectron yield (PY) spectroscopy was applied to characterize the valence band maximum (VBM) of the single crystal TiO2. [See more]

T. Toyoda, W. Yindeesuk, K. Kamiyama, S. Hayase, Q. Shen
イメージ写真2

Fig. SEM images of TiO2 electrodes: high magnification of NT
Photoacoustic spectroscopy of TiO2 nanotube electrode adsorbed with CdSe quantum dots and its photovoltaic properties
We report on the optical absorption properties and photovoltaic characteristics of nanotube (NT) TiO2 electrodes adsorbed with CdSe quantum dots (QDs), and compared them with those of nanoparticle (NP) TiO2 electrodes adsorbed with CdSe QDs. The CdSe QDs were grown directly on the TiO2 electrodes by the successive ionic layer adsorption and reaction (SILAR) method. [See more]

M. Akimoto, Q. Shen, S. Hayase, T. Toyoda
イメージ写真2
Fig. Scanning electron microscopy (SEM) image of IO-TiO2
Optical absorption of CdSe quantum dots on electrodes with different morphology
We have studied the optical absorption of CdSe quantum dots (QDs) adsorbed on inverse opal TiO2 (IO-TiO2) and nanoparticulate TiO2 (NP-TiO2) electrodes using photoacoustic (PA) measurements. The CdSe QDs were grown directly on IO-TiO2 and NP-TiO2 electrodes by a successive ionic layer adsorption and reaction (SILAR) method with different numbers of cycles. The average diameter of the QDs was estimated by applying an effective mass approximation to the PA spectra.The increasing size of the QDs with increasing number of cycles was confirmed by a redshift in the optical absorption spectrum. [See more]

W. Yindeesuk, Q. Shen, S. Hayase, T. Toyoda
    
イメージ写真2
Fig. NT-TiO2 prepared at a deposition temperature of 10°C adsorbed with CdSe ( 50,000)
Effect of defects in TiO2 nanotube thin filmon the photovoltaic properties
of quantum dot-sensitized solar cells
In the liquid-phase-deposition (LPD) method, the deposition temperature is considered to be one of the most important factors in TiO2 nanotube crystal growth. We investigated the effects of the deposition temperature on the surface morphology and defects in TiO2 nanotube (NT–TiO2) thin film electrodes utilizing scanningelectron- microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL), together with the effects of these on the photovoltaic characteristics of CdSe quantum dot (QD)-sensitized NT–TiO2 solar cells. In addition, we studied the effect of these defects on the physical properties, such as the carrier recombination and electron transport at the TiO2 and TiO2/QD interface.
[See more]

M. Akimoto, T. Toyoda, T. Okuno, S. Hayase, Q. Shen


ページトップへ戻る