18 research outputs found
Cosensitization of D‑A-π‑A Quinoxaline Organic Dye: Efficiently Filling the Absorption Valley with High Photovoltaic Efficiency
In
the efficient cosensitization, the pure organic sensitizers with high
molecular extinction coefficients and long wavelength response are
highly preferable since the dye loading amount for each dye in cosensitization
is decreased with respect to single dye sensitization. A D-A-π-A
featured quinoxaline organic sensitizer <b>IQ21</b> is specifically
designed. The high conjugation building block of 4<i>H</i>-cyclopenta[2,1-<i>b</i>:3,4-<i>b</i>′]dithiophene
(CPDT) is introduced as the π bridge, instead of the traditional
thiophene unit, especially in realizing high molecular extinction
coefficients (up to 66 600 M<sup>–1</sup> cm<sup>–1</sup>) and extending the light response wavelength. With respect to the
reference dye <b>IQ4</b>, the slightly lower efficiency of <b>IQ21</b> (9.03%) arises from the decrease of <i>V</i><sub>OC</sub>, which offsets the gain in <i>J</i><sub>SC</sub>. While cosensitized with a smaller D-π-A dye <b>S2</b>, the efficiency in <b>IQ21</b> is further improved to 10.41%
(<i>J</i><sub>SC</sub> = 19.8 mA cm<sup>–2</sup>, <i>V</i><sub>OC</sub> = 731 mV, FF = 0.72). The large improvement
in efficiency is attributed to the well-matched molecular structures
and loading amounts of both dyes in the cosensitization system. We
also demonstrated that coabsorbent dye <b>S2</b> can distinctly
compensate the inherent drawbacks of <b>IQ21</b>, not only enhancing
the response intensity of IPCE, making up the absorption defects around
low wavelength region of IPCE, but also repressing the charge recombination
rate to some extent
Porphyrins Containing a Triphenylamine Donor and up to Eight Alkoxy Chains for Dye-Sensitized Solar Cells: A High Efficiency of 10.9%
Porphyrins
are promising DSSC sensitizers due to their structural similarity
to chlorophylls as well as their tunable strong absorption. Herein,
a novel D−π–A porphyrin dye <b>XW14</b> containing
a strongly electron-donating triphenylamine moiety as the electron
donor was designed and synthesized. To avoid undesirably decreased <i>V</i><sub>oc</sub> caused by dye aggregation effect, two methoxy
or hexyloxy chains were introduced to the <i>para</i> positions
of the triphenylamine moiety to afford <b>XW15</b> and <b>XW16</b>, respectively. To further extend the absorption to a
longer wavelength, a benzothiadiazole unit was introduced as an auxiliary
acceptor to furnish <b>XW17</b>. Compared with <b>XW14</b>, the introduction of additional methoxy or hexyloxy groups in <b>XW15</b> and <b>XW16</b> red-shift the onset wavelengths
from 760 to 780 and 790 nm, respectively. More impressively, <b>XW17</b> has a more extended π-conjugation framework, and
thus, it exhibits a much broader IPCE spectrum with an extremely red-shifted
onset wavelength of 830 nm, resulting in the highest <i>J</i><sub>sc</sub> (18.79 mA cm<sup>–2</sup>). On the other hand,
the hexyloxy chains are favorable for suppressing the dye aggregation
effect, and thus <b>XW16</b> shows the highest <i>V</i><sub>oc</sub> of 734 mV. As a result, <b>XW16</b> and <b>XW17</b> demonstrate photovoltaic efficiencies of 9.1 and 9.5%,
respectively, higher than those of <b>XW14</b> (8.6%) and <b>XW15</b> (8.7%), and obviously higher than that of 7.94% for our
previously reported dye, <b>XW4</b>. On the basis of optimized
porphyrin dye <b>XW17</b>, we used a nonporphyrin dye with a
high <i>V</i><sub>oc</sub> and strong absorption around
500 nm (<b>WS-5</b>) as the cosensitizer to improve the <i>V</i><sub>oc</sub> from 700 to 748 mV, with synergistical <i>J</i><sub>sc</sub> enhancement from 18.79 to 20.30 mA cm<sup>–2</sup>. Thus, the efficiency was dramatically enhanced to
10.9%, which is among the highest efficiencies obtained for the DSSCs
based on traditional iodine electrolyte. In addition, the DSSCs based
on <b>XW17</b> + <b>WS-5</b> exhibit good photostability,
which is beneficial for practical applications
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Rational Molecular Engineering of Indoline-Based D‑A-π‑A Organic Sensitizers for Long-Wavelength-Responsive Dye-Sensitized Solar Cells
Indoline-based
D-A-π-A organic sensitizers are promising candidates for highly
efficient and long-term stable dye-sensitized solar cells (DSSCs).
In order to further broaden the spectral response of the known indoline
dye <b>WS-2</b>, we rationally engineer the molecular structure
through enhancing the electron donor and extending the π-bridge,
resulting in two novel indoline-based D-A-π-A organic sensitizers <b>WS-92</b> and <b>WS-95</b>. By replacing the 4-methylphenyl
group on the indoline donor of <b>WS-2</b> with a more electron-rich
carbazole unit, the intramolecular charge transfer (ICT) absorption
band of dye <b>WS-92</b> is slightly red-shifted from 550 nm
(<b>WS-2</b>) to 554 nm (<b>WS-92</b>). In comparison,
the incorporation of a larger π-bridge of cyclopentadithiophene
(CPDT) unit in dye <b>WS-95</b> not only greatly bathochromatically
tunes the absorption band to 574 nm but also largely enhances the
molar extinction coefficients (ε), thus dramatically improving
the light-harvesting capability. Under the standard global AM 1.5
solar light condition, the photovoltaic performances of both organic
dyes have been evaluated in DSSCs on the basis of the iodide/triiodide
electrolyte without any coadsorbent or cosensitizer. The DSSCs based
on <b>WS-95</b> display better device performance with power
conversion efficiency (η) of 7.69%. The additional coadsorbent
in the dye bath of <b>WS-95</b> does not improve the photovoltaic
performance, indicative of its negligible dye aggregation, which can
be rationalized by the grafted dioctyl chains on the CPDT unit. The
cosensitization of <b>WS-95</b> with a short absorption wavelength
dye <b>S2</b> enhances the IPCE and improves the η to
9.18%. Our results indicate that extending the π-spacer is more
rational than enhancing the electron donor in terms of broadening
the spectral response of indoline-based D-A-π-A organic sensitizers
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Light-Reconfiguring Inhomogeneous Soft Helical Pitch with Fatigue Resistance and Reversibility
Active engineering and modulation of optical spectra
in a remote
and fully reversible light is urgently desired in photonics, chemistry,
and materials. However, the real-time regulation of multiple optical
information such as wavelength, bandwidth, reflectance, and polarization
is still a longstanding issue due to the lack of an appropriate photoresponsive
candidate. Herein, we propose an additional “degree-of-freedom
(DOF)” in a photo-modulated soft helix, and build up an unprecedented
inhomogeneous helical pitch length with light-reconfiguring property,
fatigue resistance, and reversibility. For the working model, the
intrinsic chiral photoswitch LBC5 is employed as an actuator
to modulate the helical pitch length, which is proportional to the
irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted
light to decrease its intensity along the sample thickness, therefore
successfully adding another controlled DOF on the pitch length distribution
(i.e., homogeneous or inhomogeneous) apart from the common soft helix
with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables
the light to reconfigure the helical pitch from homogeneous to inhomogeneous,
thereby achieving the robust fatigue-resistance establishment of reversible
spectral programming. The established light-reconfigurable inhomogeneous
helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality,
especially for dynamically broadening and narrowing the bandwidth
on demand, and further enable the ever-desired broadband NIR circularly
polarized luminescence (CPL) with a high dissymmetry factor glum of up to 1.88. The cutting-edge photoswitchable
inhomogeneous soft helical pitch provides access to multi-freedom
control in soft materials, optics, biophotonics, and other relevant
fields
Porphyrin Cosensitization for a Photovoltaic Efficiency of 11.5%: A Record for Non-Ruthenium Solar Cells Based on Iodine Electrolyte
Dye-sensitized
solar cells (DSSCs) are promising for utilizing
solar energy. To achieve high efficiencies, it is vital to synergistically
improve the photocurrent (<i>J</i><sub>sc</sub>) and the
photovoltage (<i>V</i><sub>oc</sub>). In this respect, conjugation
framework extension and cosensitization are effective for improving
the absorption and the <i>J</i><sub>sc</sub>, which, however,
is usually accompanied by undesirably decreased <i>V</i><sub>oc</sub>. Herein, based on a rationally optimized porphyrin
dye, we develop a targeted coadsorption/cosensitization approach for
systematically improving the <i>V</i><sub>oc</sub> from
645 to 727, 746, and 760 mV, with synergistical <i>J</i><sub>sc</sub> enhancement from 18.83 to 20.33 mA cm<sup>–2</sup>. Thus, the efficiency has been dramatically enhanced to 11.5%, which
keeps the record for nonruthenium DSSCs using the I<sub>2</sub>/I<sub>3</sub><sup>–</sup> electrolyte. These results compose an
alternative approach for developing highly efficient DSSCs with relatively
high <i>V</i><sub>oc</sub> using traditional iodine electrolyte