Browsing by Author "Diau, Eric W. -G."

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Interfacial Investigation on Printable Carbon-Based Mesoscopic Perovskite Solar Cells with NiOx/C Back Electrode
(2017-08-02)
Behrouznejad, Fatemeh
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Tsai, Cheng-Min
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Narra, Sudhakar
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Diau, Eric W. -G.
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Taghavinia, Nima
Solar cells with high efficiency, low cost, and high stability are the target for the new generation of solar cells. A fully printable perovskite (CH3NH3PbI3) solar cell (PSC) with device architecture FTO/TiO2/Al2O3/NiOx/C is fabricated in the current research as a low-cost and relatively stable structure and is investigated to determine how different fabrication factors such as the thickness of the insulating spacer layer (Al2O3) or treatments such as heat and UV-O-3 treatments can affect the interfacial properties of this multilayer mesoporous structure. X-ray photoelectron spectra (XPS) show that UV-O-3 treatment increases the Ni3+ (Ni2O3) phase on the surface of the black nickel oxide layer leading to better charge extraction and increasing open-circuit voltage (V-OC) up to 0.945 V. We observe improved CH3NH3PbI3 formation inside the mesoporous layers by the PbI2 penetration at a higher temperature. Impedance spectral together with current-voltage measurements show the effect of thickness for the insulator layer in the internal and interfacial resistances and photovoltaic characteristics of the cell. The best performance of the carbon-based PSC attains power conversion efficiency of 12.1% with the thickness of the Al2O3 layer at 450 nm.
Rapid preparation of highly luminescent CdTe nanocrystals in an ionic liquid via a microwave-assisted process
(2011)
Hayakawa, Yu
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Nonoguchi, Yoshiyuki
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Wu, Hui-Ping
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Diau, Eric W. -G.
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Nakashima, Takuya
Thiol-capped CdTe nanocrystals are synthesized directly in an ionic liquid by means of microwave irradiation in a similar manner to an aqueous synthetic route. The combination of ionothermal synthesis with microwave heating offers a quick route to highly luminescent CdTe nanocrystals with zincblende crystal structure. The growth of nanocrystals is considered based on a universal growth model under the assumption that the growth rate exponentially converges as the reaction proceeds. The analysis indicates that the ionothermal conditions with high temperature promote the steady growth of nanocrystals after the nucleation, while the microwave irradiation plays a pivotal role in the limiting step of the growth of nanocrystals including the activation of nanocrystal precursor and the subsequent formation of nuclei.