Abstract:A series of unsymmetrical arene-1,3-squaraine (USQ) derivatives with two, three, or four hydroxy (-OH) substituents, namely, USQ-2-OH, USQ-3-OH, or USQ-4-OH, respectively, were designed and synthesized, and the effect of the number of hydroxy groups on the optoelectronic properties of USQs were investigated. Despite the three compounds having similar UV/Vis absorption and HOMO energy levels, solution-processed bulk-heterojunction (BHJ) small-molecule organic solar cells with USQ-3-OH as electron-donor material… Show more
“…Binary and ternary BHJ cells were fabricated with USQ3OH and/or IDPSQ as the electron donor and PC 71 BM as the electron acceptor. On the basis of our previous results, the optimal D:A ratio of 1:3 was employed in this study. , A conventional device structure comprising ITO/MoO 3 (8 nm)/blend (∼80 nm)/LiF (0.8 nm)/Al (100 nm) was employed. The photovoltaic data for all devices are summarized in Tables and S2, and representative current density–voltage ( J – V ) and external quantum efficiency (EQE)–wavelength curves are shown in Figures , S1, and S2.…”
Section: Resultsmentioning
confidence: 99%
“…USQ3OH and IDPSQ were synthesized and purified according to published methods. Both squaraines can be easily prepared without any highly toxic reagents or complex reaction schemes, which are critical issues for ultimate manufacture.…”
Ternary bulk-heterojunction
organic solar cells (BHJ-OSCs) are
demonstrated by combining two squaraine donors (USQ3OH and IDPSQ)
having complementary optical absorption and PC71BM as the
acceptor. While the corresponding binary cells exhibit maximum power
conversion efficiencies (PCEs) of 4.65% (IDPSQ binary) and 6.85% (USQ3OH
binary), the ternary cells of weight composition IDPSQ:USQ3OH:PC71BM = 0.15:1.0:3.0 (15%TB, TB = ternary blend) exhibit
a PCE of 7.20%, which is the highest known value to date for a squaraine
OSC. Single crystals of both squaraines and space-charge-limited current
(SCLC) measurements explain the efficiency difference between the
binary cells. SCLC measurements and transmission electron microscopy
imaging of the ternary devices indicate that the charge mobility slightly
increases and the BHJ domain size optimizes for the 15%TB device vs
that based on the USQ3OH blend. Grazing incidence wide-angle X-ray
scattering data reveal that enhanced π–π stacking
and larger correlation lengths can be achieved after thermal annealing
of the ternary blend film. Charge recombination measurements demonstrate
that IDPSQ can be incorporated into the blend without increasing charge
recombination. Finally, flexible OSCs on PET (polyethylene terephthalate)
with a PCE of ∼4.5% were fabricated. This study demonstrates
that readily accessible squaraine cores represent a viable choice
for the design of new organic solar cell donor materials.
“…Binary and ternary BHJ cells were fabricated with USQ3OH and/or IDPSQ as the electron donor and PC 71 BM as the electron acceptor. On the basis of our previous results, the optimal D:A ratio of 1:3 was employed in this study. , A conventional device structure comprising ITO/MoO 3 (8 nm)/blend (∼80 nm)/LiF (0.8 nm)/Al (100 nm) was employed. The photovoltaic data for all devices are summarized in Tables and S2, and representative current density–voltage ( J – V ) and external quantum efficiency (EQE)–wavelength curves are shown in Figures , S1, and S2.…”
Section: Resultsmentioning
confidence: 99%
“…USQ3OH and IDPSQ were synthesized and purified according to published methods. Both squaraines can be easily prepared without any highly toxic reagents or complex reaction schemes, which are critical issues for ultimate manufacture.…”
Ternary bulk-heterojunction
organic solar cells (BHJ-OSCs) are
demonstrated by combining two squaraine donors (USQ3OH and IDPSQ)
having complementary optical absorption and PC71BM as the
acceptor. While the corresponding binary cells exhibit maximum power
conversion efficiencies (PCEs) of 4.65% (IDPSQ binary) and 6.85% (USQ3OH
binary), the ternary cells of weight composition IDPSQ:USQ3OH:PC71BM = 0.15:1.0:3.0 (15%TB, TB = ternary blend) exhibit
a PCE of 7.20%, which is the highest known value to date for a squaraine
OSC. Single crystals of both squaraines and space-charge-limited current
(SCLC) measurements explain the efficiency difference between the
binary cells. SCLC measurements and transmission electron microscopy
imaging of the ternary devices indicate that the charge mobility slightly
increases and the BHJ domain size optimizes for the 15%TB device vs
that based on the USQ3OH blend. Grazing incidence wide-angle X-ray
scattering data reveal that enhanced π–π stacking
and larger correlation lengths can be achieved after thermal annealing
of the ternary blend film. Charge recombination measurements demonstrate
that IDPSQ can be incorporated into the blend without increasing charge
recombination. Finally, flexible OSCs on PET (polyethylene terephthalate)
with a PCE of ∼4.5% were fabricated. This study demonstrates
that readily accessible squaraine cores represent a viable choice
for the design of new organic solar cell donor materials.
“…recently synthesized SQ48–SQ50 with two, three or four hydroxy substituents, respectively. [ 68 ] They found that despite the number of OH groups had a negligible influence on the absorption and HOMO energy levels, the trihydroxy‐substituted SQ49‐based devices interestingly showed the best photovoltaic performance with a PCE of 6.07% and a J SC of 14.95 mA cm −2 . The detailed morphological study showed that the smaller phase separation for the SQ49/PC 71 BM blended film made a major contribution to enhanced device performance as shown in Figure 8c,d.…”
Section: Squaraine‐based Functional Materials For Photovoltaic Applicmentioning
Squaraine dyes (SQs) are an important class of polymethine dyes with a unique reasonable‐stabilized zwitterionic structure, in which electrons are highly delocalized over the conjugated bridge. These dyes can not only be easily synthesized via a condensation, but also exhibit intense absorption and emission in the visible and near‐infrared region with excellent photochemical stability, making them attractive material candidates for many photoelectric and biomedical applications. Thus, in this review, after an introduction of SQs, the recent advances of SQs in the photovoltaic field are comprehensively summarized including dye‐sensitized solar cells, organic solar cells, and perovskite solar cells. Then, the important advances in the use of SQs as the biosensors, biological imaging, and photodynamic/photothermal therapy reagents in the biomedical field are also discussed. Finally, a summary and outlook will be provided with some new perspectives for the future design of SQs.
“…A breakthrough was made in 2008; Marks et al developed a new type of hydrazine end‐capped SQs as the donor materials in the bulk heterojunction (BHJ) OSCs, and an encouraging PCE of 1.24% was produced. Subsequently, the photovoltaic performance of SQs has been gradually elevated with further development of new material exploitation and device engineering . Thus far, PCEs over 7% have been demonstrated in both single‐junction and tandem BHJ devices merely with SQs as the donors .…”
So far, squaraine‐based polymer donors have been less explored for the bulk heterojunction (BHJ) polymer solar cells. In this work, two new p–π conjugated polysquaraines (PASQ‐BDT1 and PASQ‐BDT2) with different electron‐rich subunits on the squaraine skeleton are rationally developed as new polymer donors based on the 2D structure design concept. PASQ‐BDT2 with N,N‐diisobutylaniline subunits shows superior device performances in both fullerene and nonfullerene PSCs compared to PASQ‐BDT1 containing triphenylamine subunits, with power conversion efficiencies (PCEs) of 4.34% and 3.72%, respectively, owing to increased light‐harvesting ability and more favorable nanoscale morphology in the BHJ films. Moreover, its demonstrated that solvent effects can play an effective role in elevating the device performance. For the PASQ‐BDT2/PC71BM blend, the PCE is improved from 3.19% to 4.34% after solvent vapor annealing treatment, mainly attributed to the optimized film morphology and increased hole mobility. More interestingly, when the processing solvent for nonfullerene devices is changed from chlorobenzene to chloroform, a significant enhancement on PCE from 1.96% to 3.72% is yielded for the PASQ‐BDT2/ITIC blend, due to suppressed charge recombination and enhanced crystallinity in the chloroform‐processed BHJ films.
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