Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Molecular Engineering of Highly Efficient Small Molecule Nonfullerene Acceptor for Organic Solar Cells

A new molecularly engineered nonfullerene acceptor, 2,2'-(5,5'-(9,9-didecyl-9H-fluorene-2,7-diyl) bis(benzo[c][1,2,5] thiadiazole7,4-diyl) bis(methanylylidene)) bis(3-hexyl-1,4-oxothiazolidine-5,2-diylidene)) dimalononitrile (BAF-4CN), with fluorene as the core and arms of dicyanon- hexylrhodanine terminated benzothiadiazole is synthesized and used as an electron acceptor in bulk heterojunction organic solar cells. BAF-4CN shows a stronger and broader absorption with a high molar extinction coefficient of 7.8 x 10(4) m(-1) cm(-1) at the peak position (498 nm). In the thin film, the molecule shows a redshift around 17 nm. The photoluminescence experiments confirm the excellent electron accepting nature of BAF-4CN with a Stern-Volmer coefficient (K-sv) of 1.1 x 10(5) m(-1). From the electrochemical studies, the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of BAF-4CN are estimated to be -5.71 and -3.55 eV, respectively, which is in good synchronization with low bandgap polymer donors. Using BAF-4CN as an electron acceptor in a poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'''-di(2-octyldodecyl) 2,2; 5', 2 ''; 5 '', 2'''-quaterthiophen-5,5'''-diyl)] based bulk-heterojunction solar cell, a maximum power conversion efficiency of 8.4% with short-circuit current values of 15.52 mA cm(-2), a fill factor of 70.7%, and external quantum efficiency of about 84% covering a broad range of wavelength is achieved

A highly efficient PTB7-Th polymer donor bulk hetero-junction solar cell with increased open circuit voltage using fullerene acceptor CN-PC70BM

Modified [6,6] -phenyl-C-70-butyric acid methyl ester (CN-PC70BM) is employed as an electron acceptor along with poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b; 4,5-b]clithiophene-2,6-diy]-alt-(4(2-ethylhexyl)-3-fluorothieno[3,4-6]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th) polymer as donor for solution-processed organic solar cells. Inverted device architecture is adopted to fabricate the photovoltaic devices. Using chloronaphthalene as an additive, a high power conversion efficiency (PCE) of 8.2% is achieved with an excellent open circuit voltage (V-oc) of 0.9 V, short-circuit current density (J(sc)) of 13.5 mA cm(-2) and fill factor of 0.68 as compared to PCE of 5.4% from the reference solar cell using PC70BM

A simple fluorene core-based non-fullerene acceptor for high performance organic solar cells

A small molecule non-fullerene acceptor based on a fluorene core having a furan pi-spacer and end capped with rhodanine (FRd(2)) is developed for solution processable bulk heterojunction organic solar cells (OSCs). The simplistic synthetic protocol reduces several reaction steps and hence production cost. Extended pi-conjugation via furan units and the presence of electronegative rhodanine groups result in a power conversion efficiency of 9.4% in OSCs, which is the highest so far among these categories of molecules

High-Performance Non-Fullerene Acceptor Derived from Diathiafulvalene Wings for Solution-Processed Organic Photovoltaics

A solution-processable small-molecule nonfullerene electron acceptor BAF-2HDT (7,7'-(9,9-didecyl-9H-fluorene-2,7-diyl)bis(4-((4,5-bis(hexylthio)-1,3-dithiol-2 ylidene)methyl)benzo[c][1,2,5]thiadiazole) bearing hexadiathiafulvalene (HDT) wings as end groups has been synthesized for bulk heterojunction organic photovoltaics. The molecule shows broad absorption in the 300-600 nm range with a molar extinction coefficient (epsilon) of 9.32 X 10(4) M-1.cm(-1) exceeding to that of [6,6]-phenyl-C-71-butyric acid methyl ester of 2.8 X 10(4) M-1.cm(-1) at 461 nm. The HOMO and LUMO energy levels of the molecule are found to be -5.69 and -3.58 eV, respectively which is compatible with low band gap high-performance polymers such as poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3 '''-di(2-octyldodecyl)-2,2';5',2 '';5 '',2 '''- quaterthiophen-5,5 '''-diyl)] (PffBT4T-2OD). Photoluminescence-quenching measurements confirm that the molecule BAF-2HDT has excellent electron-accepting capability. The organic solar cells made from BAF-2HDT blending with conjugated polymer donor PffBT4T-2OD exhibit a power conversion efficiency of 7.13% with high V-oc of 0.77 V, J(sc) of 14.64 mA.cm(-2), and FF of 0.64. The design and development of such nonfullerene acceptors with high epsilon may be key to further development of high-performahce and cost-effective solution-processed organic solar cells

A fluorene-core-based electron acceptor for fullerene-free BHJ organic solar cells-towards power conversion efficiencies over 10%

A small molecule non-fullerene electron acceptor (SMNFEA), bearing a furan pi-spacer and dicyano-n-hexyl rhodanine as flanking groups, was designed and synthesized for organic solar cell applications. Organic photovoltaic devices based on FRdCN(2) and PTB7-Th polymer donors exhibited a highly improved efficient power conversion efficiency of 10.7%, which is the highest so far for OSCs fabricated from fluorene-core-based SMNFEA

Achieving the highest efficiency using a BODIPY core decorated with dithiafulvalene wings for small molecule based solution-processed organic solar cells

A novel boron dipyrromethene based dye, coded as BODIPY-DTF, decorated with dithiafulvalene wings has been developed for solar cell application. A very high efficiency of 7.2% has been achieved, which is the highest reported value so far for BODIPY based donors. A remarkable value of about 88.1% of external quantum efficiency has also been observed at 371 nm

New Electron Acceptor Derived from Fluorene: Synthesis and Its Photovoltaic Properties

Two new fullerene derivatives <b>N3</b> and <b>N6</b>, derived from flourene, have been synthesized for the organic photovoltaic applications. The molecule <b>N3</b> is a diarylmethano fullerene derivative, whereas <b>N6</b> contains a chromophore 4-nitro-cyaostilbene (NCS). Their optical, electrochemical, and structural properties were systematically studied by ¹H and ¹³C NMR, FT-IR, and UV–visible absorption spectroscopy. A series of bulk heterojunction polymer solar cells was constructed from these newly developed acceptors using PBDTTT-C-T and PTB7 as electron donors with different donor-to-acceptor weight ratios along with the variation in the volume percentage of DIO additive. The best solar cells made from PTB7:<b>N3</b> and PTB7:<b>N6</b> blends exhibited power conversion efficiencies of 4.1 and 3.6%, and the cells made from PBDTTT-C-T:<b>N3</b> and PBDTTT-C-T:<b>N6</b> blends exhibited power conversion efficiencies of 2.3 and 1.4%, respectively, with a very high open circuit voltage of over 0.85 V

D-pi-A-pi-D Structured Diketopyrrolopyrrole-Based Electron Donors for Solution-Processed Organic Solar Cells

Solution-processable D-pi-A-pi-D structured two organic small molecules bearing thienyl diketopyrrolopyrrole (TDPP) and furanyl diketopyrrolopyrrole (FDPP) as central acceptor units and cyano on the pi-bridge and phenothiazine as the terminal donor units, coded as TDPP-PTCN and FDPP-PTCN, are designed and synthesized. The CH arylation and Suzuki coupling protocols have been adopted for synthesizing the molecules. Solution-processed organic solar cells (OSCs) were constructed with these molecules as the donors and phenyl-C-71-butyric acid methyl ester as the acceptor yielding power conversion efficiencies (PCE) of 4.0% for FDPP-PTCN and 5.2% for TDPP-PTCN, which is the highest PCE reported so far from the small molecular DPP-phenothiazine-based architecture for solution-based OSCs. The effect of heteroatom substitution on thermal stability and optoelectronic and photovoltaic performances is also systematically investigated herein. This work demonstrates that replacement of oxygen with sulfur in these kinds of small molecules remarkably improves the photovoltaic performance of OSCs