Designing a hybrid type photoelectrochromic device with dual coloring modes for realizing ultrafast response/high optical contrast self-powered smart windows

Poly-(3,4-ethylenedioxythiophene) (PEDOT) is an ideal polymer for electrochromic (EC) devices due to its fast response time, high conductivity, and facile fabrication in a doped form except its demerit like an optical contrast limitation. In this study, we developed a simple way to overcome low coloration efficiency of PEDOT through fabricating a complementary PEDOT and prussian blue full cell system. Fundamental properties of EC displays, such as optical contrast, coloration efficiency, and switching speed, could be successfully optimized by controlling the deposition time and applied voltage during EDOT polymerization. In particular, UV transmittance spectra indicated that the optical contrast was enhanced up to 31∼99% at the wavelength of 600 nm. Scanning electron microscopy images showed that the optimized PEDOT and prussian blue films were deposited on ITO glass substrate with an uniform thickness of ∼180 nm and ∼190 nm, respectively. Moreover, according to the circuit analysis, the average response time of electric current for the optimized full cell system was about 400 ms. It is, therefore, concluded that such a full cell system could have high potential applications as smart windows and/or optical devices.

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Wide GAP a-SiC:H Alloys for Novel Photovoltaic-Electrochromic Window Coatings

MRS Proceedings ◽

10.1557/proc-377-589 ◽

1995 ◽

Vol 377 ◽

Cited By ~ 1

Author(s):

John N. Bullock ◽

Yueqin Xu ◽

David Benson ◽

Howard M. Branz

Keyword(s):

Thin Films ◽

Amorphous Silicon ◽

Optical Transmittance ◽

Open Circuit ◽

Electrochromic Device ◽

Smart Windows ◽

Silicon Carbon ◽

Wide Gap ◽

Self Powered ◽

Silicon Based

ABSTRACTSelf-powered “smart” windows utilize an electro-optic transmittance modulator based on electrochromic (EC) thin films that exhibit reversible and controlled changes in optical properties with an applied voltage between 0.7 and 2.0 V. Existing window designs require an external electrical connection, which may be economically unfeasible. This problem is solved by the tandem photovoltaic-electrochromic device, in which a wide-gap amorphous silicon-based alloy photovoltaic device is deposited together with an electrochromic optical transmittance modulator in a monolithic device on a single substrate. In this paper, we discuss our proposed monolithic photovoltaic-electrochromic device.We also present studies of transparent, wide-gap (1.8 to 2.2 eV) amorphous silicon-carbon thin films and p-i-n devices designed for use in the photovoltaic-electrochromic device. These photovoltaic cells can operate at low current (<1 mA/cm2) because a total injected charge of only 60 μC/cm2 will darken the EC layer to a visible transmission of 5%, but they need a high open-circuit voltage (>1.0 V) and high transparency (≈70%). We present our progress toward these design targetxxss.

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