4 research outputs found
Synthesis and Photovoltaic Performance of Pyrazinoquinoxaline Containing Conjugated Thiophene-Based Dendrimers and Polymers
Pyrazinoquinoxaline-based
building blocks were incorporated into
both π-conjugated dendrimers and polymers. The dendrimers were
synthesized using a convergent/divergent approach whereas the donor/acceptor
copolymers were synthesized via Stille cross-coupling reactions. The
structurally defined dendrimers and the π-conjugated polymers
were investigated with respect to their optical and electronic properties
as well as their performance in photovoltaic devices. Because of the
presence of the electron-deficient pyrazinoquinoxaline moiety, the
absorption spectra of the materials under investigation were red-shifted
with respect to the all thiophene-containing materials. Power conversion
efficiencies up to 1.7 and 0.8% were obtained from blends of second-generation
dendrimers and polymers with PC<sub>71</sub>BM, respectively
Silane-Capped ZnO Nanoparticles for Use as the Electron Transport Layer in Inverted Organic Solar Cells
Zinc
oxide (ZnO) nanoparticles are widely used as electron- transport
layer (ETL) materials in organic solar cells and are considered to
be the candidate with the most potential for ETLs in roll-to-roll
(R2R)-printed photovoltaics. However, the tendency of the nanoparticles
to aggregate reduces the stability of the metal oxide inks and creates
many surface defects, which is a major barrier to its printing application.
With the aim of improving the stability of metal oxide nanoparticle
dispersions and suppressing the formation of surface defects, we prepared
3-aminopropyltrimethoxysilane (APTMS)-capped ZnO (ZnO@APTMS) nanoparticles
through surface ligand exchange. The ZnO@APTMS nanoparticles exhibited
excellent dispersibility in ethanol, an environmentally friendly solvent,
and remained stable in air for at least one year without any aggregation.
The capping of the ZnO nanoparticles with APTMS also reduced the number
of surface-adsorbed oxygen defects, improved the charge transfer efficiency,
and suppressed the light-soaking effect. The thickness of the ZnO@APTMS
ETL could reach 100 nm without an obvious decrease in the performance.
Large-area APTMS-modified ZnO films were successfully fabricated through
roll-to-roll microgravure printing and exhibited good performance
in flexible organic solar cells. This work demonstrated the distinct
advantages of this ZnO@APTMS ETL as a potential buffer layer for printed
organic electronics
Power Conversion Efficiency and Device Stability Improvement of Inverted Perovskite Solar Cells by Using a ZnO:PFN Composite Cathode Buffer Layer
We have demonstrated in this article
that both power conversion efficiency (PCE) and performance stability
of inverted planar heterojunction perovskite solar cells can be improved
by using a ZnO:PFN nanocomposite (PFN: poly[(9,9-bis(3′-(<i>N</i>,<i>N</i>-dimethylamion)propyl)-2,7-fluorene)-<i>alt</i>-2,7-(9,9-dioctyl)-fluorene]) as the cathode buffer layer
(CBL). This nanocomposite could form a compact and defect-less CBL
film on the perovskite/PC<sub>61</sub>BM surface (PC<sub>61</sub>BM:
phenyl-C<sub>61</sub>-butyric acid methyl ester). In addition, the
high conductivity of the nanocomposite layer makes it works well at
a layer thickness of 150 nm. Both advantages of the composite layer
are helpful in reducing interface charge recombination and improving
device performance. The power conversion efficiency (PCE) of the best
ZnO:PFN CBL based device was measured to be 12.76%, which is higher
than that of device without CBL (9.00%), or device with ZnO (7.93%)
or PFN (11.30%) as the cathode buffer layer. In addition, the long-term
stability is improved by using ZnO:PFN composite cathode buffer layer
when compare to that of the reference cells. Almost no degradation
of open circuit voltage (<i>V</i><sub>OC</sub>) and fill
factor (FF) was found for the device having ZnO:PFN, suggesting that
ZnO:PFN is able to stabilize the interface property and consequently
improve the solar cell performance stability
Fully Coated Semitransparent Organic Solar Cells with a Doctor-Blade-Coated Composite Anode Buffer Layer of Phosphomolybdic Acid and PEDOT:PSS and a Spray-Coated Silver Nanowire Top Electrode
In the aim to realize
high performance semitransparent fully coated organic solar cells,
printable electrode buffer layers and top electrodes are two important
key technologies. An ideal ink for the preparation of the electrode
buffer layer for printed top electrodes should have good wettability
and negligible solvent corrosion to the underlying layer. This work
reports a novel organic–inorganic composite of phosphomolybdic
acid (PMA) and PEDOT:PSS that features excellent wettability with
the active layer and printed top Ag nanowires and high resistibility
to solvent corrosion. This composite buffer layer can be easily deposited
on a polymer surface to form a smooth, homogeneous film via spin-coating
or doctor-blade coating. Through the use of this composite anode buffer
layer, fully coated semitransparent devices with doctor-blade-coated
functional layers and spray-coated Ag nanowire top electrodes showed
the highest power conversion efficiency (PCE) of 5.01% with an excellent
average visible-light transmittance (AVT) of 50.3%, demonstrating
superior overall characteristics with a comparable performance to
and a much higher AVT than cells based on a thermally evaporated MoO<sub>3</sub>/Ag/MoO<sub>3</sub> thin film electrode (with a PCE of 5.77%
and AVT of 19.5%). The current work reports the fabrication of fully
coated inverted organic solar cells by combining doctor-blade coating
and spray coating and, more importantly, demonstrates that a nanocomposite
of a polyoxometalate and conjugated polymer could be an excellent
anode buffer layer for the fully coated polymer solar cells with favorable
interfacial contact, hole extraction efficiency, and high comparability
with full printing