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  • Nanosecond Diffuse Reflectance Spectroscopy for In-Situ Analysis of Electron Back-Recombination and Dye Regeneration in Fully Functional, Highly Efficient, Opaque Dye-Sensitized Solar Cell Devices
Title: Nanosecond Diffuse Reflectance Spectroscopy for In-Situ Analysis of Electron Back-Recombination and Dye Regeneration in Fully Functional, Highly Efficient, Opaque Dye-Sensitized Solar Cell Devices
An improved optical design for nanosecond diffuse reflectance (DR) spectroscopy is presented. The in-situ analysis of the electron back-reaction and dye regeneration processes in efficient opaque dye-sensitized solar cell devices (DSCs) was scrutinized for the first time using nanosecond DR spectroscopy. The efficient DSC device is based on an opaque TiO2 double-layer film comprising 400 nm light-scattering particles and 20 nm optically transparent particles. Transmission-based laser techniques are not suitable for studying these or other devices by using the opaque morphologies of TiO2 films. However, time-resolved DR flash photolysis enables the exploration of photophysical processes in a broad variety of opaque or highly light-absorbing and light-scattering materials. We experimentally verified the three important components of DR-based spectroscopy: optical configuration, sample condition, and theoretical quantitative optical models. The large optical angle for diffusive light enables efficient light collection and measurement at a relatively low power. We tested the steady-state and time-resolved concentration dependence of the Kubelka−Munk theory for the quantitative analysis of time-resolved results and observed that the dynamics of electron back-reactions are strongly affected by the morphological parameters of the TiO2 films. With a lifetime of 50 μs, the kinetics of electron back-recombination in the device’s photoanode, which is manufactured with 400 nm TiO2 particles and 20 nm TiO2 particles, are 2 orders of magnitude faster than what has been reported to date for 20 nm particles (1 ms). In contrast to electron back-recombination, the dye regeneration process is not influenced by the TiO2 film morphology.  more » « less
Award ID(s):
2239539
PAR ID:
10479196
Author(s) / Creator(s):
;
Editor(s):
Professor Gregory Hartland
Publisher / Repository:
The Journal of Physical Chemistry C
Date Published:
Journal Name:
The Journal of Physical Chemistry C
Volume:
127
Issue:
48
ISSN:
1932-7447
Page Range / eLocation ID:
23285 to 23295
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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