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One of the recent advances in medical nanotechnology has been the development of nanoformulations to overcome drug-resistant bacterial infections. Herein, we disclose a new nano-antibiotic formulation based on sceptrin-Au nano-aggregates (SANA), which are drug-metal ion multiple complexes. Sceptrin is a natural compound from a marine organism (sponge) and was reported as a potential compound with drug activities. SANA consists of a sceptrin-Au ion and is a self-assembled nano-formation with electrostatic interaction. Interestingly, SANA showed superior antibiotic/antibiofilm activity toward carbapenem-resistant Gram-negative bacteria with low toxicity to red blood cells and endothelial cells. The working mechanism of SANA was identified with analysis of the extracellular reactive oxygen species level and membrane depolarization of bacteria. The feasibility of SANA as a new nano-antibiotic was demonstrated in CRPA-contaminated medical supplies where SANA inhibited the formation of biofilms as well as the growth of CRPA. This work presents a new concept for the development of next-generation nano-antibiotics and a more feasible clinical translational pathway.

Compared with p-type terpolymers, less effort has been devoted to n-type analogs. Herein, we synthesized a series of n-type terpolymers via incorporating three electron-deficient third components including thienopyrroledione (TPD), phthalimide, and benzothiadiazole into an imide-functionalized parent n-type copolymer to tune optoelectronic properties without sacrificing the n-type characteristics. Due to effects of the third components with different electron-accepting ability and solubility, the resulting three polymers feature distinct energy levels and crystallinity. In addition, heteroatoms (S, O, and N) attached on the third components trigger intramolecular noncovalent interactions, which can increase molecule planarity and have a significant effect on the packing structures of the polymer films. As a result, the best power conversion efficiency of 8.28% was achieved from all-polymer solar cells (all-PSCs) based on n-type terpolymer containing TPD. This is contributed by promoted electron mobility and face-on polymer packing, showing the pronounced advantages of the TPD used as a third component for thriving efficient n-type terpolymers. The generality is also successfully validated in a benchmark polymer donor/acceptor system by introducing TPD into the benchmark n-type polymer N2200. The results demonstrate the feasibility of introducing suitable electron-deficient building blocks as the third components for high-performance n-type terpolymers toward efficient all-PSCs.

In this study, we demonstrated two deep-blue TADF emitters, BO-tCzPhICz and BO-tCzDICz, for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). They were synthesized by employing an organoboron acceptor and 9-(3,6-di

Two new Y6 derivatives of symmetrical YBO-2O and asymmetrical YBO-FO nonfullerene acceptors (NFAs) are prepared with a simplified synthetic procedure by incorporating octyl and fluorine substituents onto the terminal 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN) moiety. By moving the alkyl substituents on the Y6 core to the terminal INCN moiety, the lowest unoccupied molecular orbital of the YBO NFAs increases without decreasing solubility, resulting in high open-circuit voltages of the devices. Molecular dynamics simulation shows that YBO-2O/-FO preferentially form core-core and terminal-terminal dimeric interactions, demonstrating their tighter packing structure and higher electron mobility than Y6, which is consistent with 2D grazing incidence X-ray scattering and space charge limited current measurements. In blend films, the hole transfer (HT) from YBO-2O/-FO to the polymer donor PM6 is studied in detail by transient absorption spectroscopy, demonstrating efficient HT from YBO-FO to PM6 with their suitable energy level alignment. Despite the simplified synthesis, YBO-FO demonstrates photovoltaic performance similar to that of Y6, exhibiting a power conversion efficiency of 15.01%. Overall, this design strategy not only simplifies the synthetic procedures but also adjusts the electrical properties by modifying the intermolecular packing and energy level alignment, suggesting a novel simplified molecular design of Y6 derivatives.

Understanding and disentangling photophysical properties of long-lived photoexcitations in bulk heterojunction (BHJ) solar cells, which contribute mostly to photocurrent, provide essential guidelin...

An in-depth study on the photovoltaic characteristics under indoor lights, i.e., light-emitting diode (LED), fluorescent lamps, and halogen lamps, was performed with varying the photoactive layer thickness (120–870 nm), by comparing those under 1-sun condition. The semi-crystalline mid-gap photoactive polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) and a fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) were used as a photoactive layer. In the contrary to the measurements under 1-sun condition, the indoor devices show a clearly different behavior, showing the thickness tolerant short-circuit current density (JSC) and fill factor (FF) values with 280–870 nm thick photoactive layers. The retained JSC and FF values of thick indoor devices were discussed in terms of the parasitic resistance effects based on the single-diode equivalent circuit model. The much lower series/shunt resistance (Rs/RP) ratio was measured with thick photoactive layer (≥280 nm), resulting in negligible decreases in the JSC and FF values even with a 870-nm-thick active layer under the LED condition. Under 1000 lx LED light, the PPDT2FBT:PC70BM device showed an optimum power conversion efficiency (PCE) of 16% (max power density, 44.8 μW/cm2) with an open-circuit voltage of 587 mV, a JSC of 117 μA/cm2, and a FF of 65.2. The device with a 870-nm-thick active layer still exhibited an excellent performance with a PCE of 12.5%. These results clearly suggest that the critical parasitic resistance effects on the performance vary depending on the light illumination condition, and the large RP associated with the viable thick photoactive layer and the well-matched absorption (of photoactive layer) with the irradiance spectrum (of indoor light) are essential to realize efficient indoor photovoltaic cells with high JSC and FF.

A new indacenodithiophene-based acceptor–donor–acceptor (A–D–A) type nonfullerene acceptor material ITBTC, featuring a conjugation-extended benzo[b]thiophene-fused end group, was designed and synthesized. Compared to the well known phenyl-fused ITIC acceptor containing a 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) end group, incorporation of an additional electron-rich thiophene into the IC moiety decreased the electron-accepting strength of the end group and increased the intermolecular interactions of ITBTC molecules. As a result, ITBTC exhibited an elevated lowest unoccupied molecular orbital, an improved electron mobility, and a more favorable blend film morphology. Despite its slightly blue-shifted absorption, the photocurrent of ITBTC-based devices was well-maintained due to the extra absorption band in the short wavelength range, which is induced by its conjugation-extended end group. Benefitting from these characteristics, the ITBTC-based solar cells achieved an enhanced power conversion efficiency (PCE) of 10.99% with a simultaneously improved open-circuit voltage (Voc, 0.94 V) and fill factor (FF, 71.3%) and well-maintained short-circuit current density (Jsc, 16.37 mA cm−2), compared to those of the ITIC-based devices (PCE of 9.53%). These results suggest that extending the π-conjugation of end group through thiophene incorporation is an efficient approach for optimizing both the energy level alignment and intermolecular interaction of the acceptor materials while maintaining their efficient light-harvesting ability. Our study also demonstrates the great potential of the new benzo[b]thiophene-fused end group for constructing high-performance nonfullerene acceptors and provided insight into overcoming the trade-off between Jsc and Voc to realize simultaneously enhanced photovoltaic parameters.

Organic solar cells based on bulk heterojunctions (BHJs) are attractive energy-conversion devices that can generate electricity from absorbed sunlight by dissociating excitons and collecting charge carriers. Recent breakthroughs attained by development of nonfullerene acceptors result in significant enhancement in power conversion efficiency (PCEs) exceeding 17%. However, most of researches have focused on pursuing high efficiency of small-area (

A new polymer acceptor poly{(N,N'-bis(2-ethylhexyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl)-alt-5,5-(3,3'-didodecyl-2,2'-bifuran)} (NDI-BFR) made from naphthalenediimide (NDI) and furan-derived head-to-head-linked 3,3'-dialkyl-2,2'-bifuran (BFR) units is reported in this study. Compared to the benchmark polymer poly(naphthalenediimide-alt-bithiophene) (N2200), NDI-BFR exhibits a larger bathochromic shift of absorption maxima (842 nm) with a much higher absorption coefficient (7.2 × 104 m-1 cm-1 ), leading to an ultranarrow optical bandgap of 1.26 eV. Such properties ensure good harvesting of solar light from visible to the near-infrared region in solar cells. Density functional theory calculation reveals that the polymer acceptor NDI-BFR possesses a higher degree of backbone planarity versus the polymer N2200. The polymer NDI-BFR exhibits a decent electron mobility of 0.45 cm2 V-1 s-1 in organic thin-film transistors (OTFTs), and NDI-BFR-based all-polymer solar cells (all-PSCs) achieve a power conversion efficiency (PCE) of 4.39% with a very small energy loss of 0.45 eV by using the environmentally friendly solvent 1,2,4-trimethylbenzene. These results demonstrate that incorporating head-to-head-linked BFR units in the polymer backbone can lead to increased planarity of the polymer backbone, reduced optical bandgap, and improved light absorbing. The study offers useful guidelines for constructing n-type polymers with narrow optical bandgaps.

In this study, we synthesized two acceptor-donor-acceptor (A-D-A)-type small molecules (SMs) (P3T4-VCN and P3T4-INCN) with different terminal end-groups (dicyanovinyl (VCN) and 2-methylene-3-(1,1-dicyanomethylene)indanone (INCN)) based on the 1,4-bis(thiophenylphenylthiophene)-2,5-difluorophenylene (P3T4) core that possesses high coplanarity because of intrachain noncovalent Coulombic interactions. We investigated the influence of terminal end-groups on intermolecular packing and the resulting electrical and photovoltaic characteristics. A small change in the end-group structure of the SMs induces a significant variation in the torsional structures, molecular packing, and pristine/blend film morphology. It is noteworthy that the less crystalline P3T4-INCN with tilted conformation is highly sensitive to post-treatments (i.e., additives and annealing) such that it permits facile morphological modulation. However, the highly planar and crystalline P3T4-VCN exhibits a strong tolerance toward processing treatments. After morphology optimization, the fullerene-based bulk-heterojunction solar cell of tilted P3T4-INCN exhibits a power conversion efficiency (PCE) of 5.68%, which is significantly superior to that of P3T4-VCN:PC71BM (PCE = 1.29%). Our results demonstrate the importance of the terminal end-group for the design of A-D-A-type SMs and their sensitivity toward the postprocessing treatments in optimizing their performance.

A novel strategy involving judiciously fusing one thiophene/thieno[3,2-b]thiophene on only one side of an indacenodithiophene (IDT) unit to extend IDT backbone conjugation was developed, and three A–D–A type non-fullerene small molecules (TPT-2F, TPTT-2F, and TPTTT-2F) were designed and synthesized to investigate the influence of the extent of IDT core conjugation on their photovoltaic properties. Extending the IDT core conjugation could broaden absorption, upshift the lowest unoccupied molecular orbital (LUMO) energy level, enhance electron mobility, and increase intermolecular π–π stacking. When these three non-fullerene acceptors were applied in organic solar cells (OSCs), simultaneous enhancement of the open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF) was obtained, with the degree of enhancement following the order TPT-2F < TPTT-2F < TPTTT-2F. As a result, the TPTTT-2F based OSCs yielded a high PCE of 12.03%. To the best of our knowledge, the PCE of 12.03% is among the highest values for asymmetric non-fullerene acceptor based OSCs so far. These results demonstrate that extending the conjugation of the IDT core is an effective approach to design highly efficient asymmetric non-fullerene acceptors.

Hot solution deposition has emerged as a promising strategy to achieve high performance polymer solar cells and many state-of-the-art devices have been recently fabricated by this approach in research laboratories. Currently, a major challenge in the photovoltaics community is translating such methodologies into industrially relevant processes so that progress can be made beyond the research community. In this work, hot deposition is developed via a slot die coating process, using a thermally robust and thickness tolerant photovoltaic polymer and a 3D printer-based slot die coater. This method uses not only hot substrates but also hot solutions. We find that controlling solution and substrate temperatures is critical to achieve optimum morphology and high device performance. Analysis of nano-morphology and molecular packing shows a clear influence of both solution and substrate temperatures. At optimal temperature conditions (80 °C head−80 °C substrate), slot die coated devices with an inverted configuration exhibited up to a 7.61% power conversion efficiency without using additives or other processing treatments, which are detrimental to stability and processing efficiency. The optimum temperature combination was readily scaled up using roll-to-roll processing equipment without further optimization, yielding flexible polymer solar cells with a 7.06% power conversion efficiency, demonstrating the potential of the hot slot die coating method from an industrial perspective.

Halogenated solvents are prevailingly used in the fabrication of nonfullerene organic solar cells (NF-OSCs) at the current stage, imposing significant restraints on their practical applications. By copolymerizing phthalimide or thieno[3,4

In article number 1801743, Xugang Guo and co‐workers develop two phthalimide‐based polymers featuring a D‐A1‐D‐A2 backbone motif. Eliminating benzodithiophene leads to polymers with substantial mobility. Nonfullerene polymer solar cells utilizing these high‐mobility polymers achieve a remarkable power conversion efficiency >13%. The results demonstrate that phthalimides are excellent building blocks for enabling polymer semiconductors with outstanding solar cell performances and benzodithiophenes are not necessary for constructing such polymers.

A novel imide-functionalized arene, di(fluorothienyl)thienothiophene diimide (f-FBTI2), featuring a fused backbone functionalized with electron-withdrawing F atoms, is designed, and the synthetic challenges associated with highly electron-deficient fluorinated imide are overcome. The incorporation of f-FBTI2 into polymer affords a high-performance n-type semiconductor f-FBTI2-T, which shows a reduced bandgap and lower-lying lowest unoccupied molecular orbital (LUMO) energy level than the polymer analog without F or with F-functionalization on the donor moiety. These optoelectronic properties reflect the distinctive advantages of fluorination of electron-deficient acceptors, yielding "stronger acceptors," which are desirable for n-type polymers. When used as a polymer acceptor in all-polymer solar cells, an excellent power conversion efficiency of 8.1% is achieved without any solvent additive or thermal treatment, which is the highest value reported for all-polymer solar cells except well-studied naphthalene diimide and perylene diimide-based n-type polymers. In addition, the solar cells show an energy loss of 0.53 eV, the smallest value reported to date for all-polymer solar cells with efficiency > 8%. These results demonstrate that fluorination of imide-functionalized arenes offers an effective approach for developing new electron-deficient building blocks with improved optoelectronic properties, and the emergence of f-FBTI2 will change the scenario in terms of developing n-type polymers for high-performance all-polymer solar cells.

Head-to-head linked bithiophenes with planar backbones hold distinctive advantages for constructing organic semiconductors, such as good solubilizing capability, enabling narrow bandgap, and effective tuning of frontier molecular orbital (FMO) levels using minimal thiophene numbers. In order to realize planar backbone, alkoxy chains are typically installed on thiophene head positions, owing to the small van der Waals radius of oxygen atom and accompanying noncovalent S⋯O interaction. However, the strong electron donating alkoxy chains on the electron-rich thiophenes lead to elevated FMO levels, which are detrimental to material stability and device performance. Thus, a new design approach is needed to counterbalance the strong electron donating property of alkoxy chains to bring down the FMOs. In this study, we designed and synthesized a new head-to-head linked building block, 4-alkoxy-5-(3-alkylthiophen-2-yl)thiazole (TRTzOR), using an electron-deficient thiazole to replace the electron-rich thiophene. Compared to previously reported 3-alkoxy-3′-alkyl-2,2′-bithiophene (TRTOR), TRTzOR is a weaker electron donor, which considerably lowers FMOs and maintains planar backbone through the noncovalent S⋯O interaction. The new TRTzOR was copolymerized with benzothiadiazoles with distinct F numbers to yield a series of polymer semiconductors. Compared to TRTOR-based analogous polymers, these TRTzOR-based polymers have broader absorption up to 950 nm with lower-lying FMOs by 0.2–0.3 eV, and blending these polymers with PC71BM leads to polymer solar cells (PSCs) with improved open-circuit voltage (Voc) by ca. 0.1 V and a much smaller energy loss (Eloss) as low as 0.59 eV. These results demonstrate that thiazole substitution is an effective approach to tune FMO levels for realizing higher Vocs in PSCs and the small Eloss renders TRTzOR a promising building block for developing high-performance organic semiconductors.

A face-on oriented and p-doped semicrystalline conjugated polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]-thiadiazole)] (PPDT2FBT), was studied as a hole-transport layer (HTL) in methylammonium lead triiodide-based perovskite solar cells (PVSCs). PPDT2FBT exhibits a mid-band gap (1.7 eV), high vertical hole mobility (7.3 × 10–3 cm2/V·s), and well-aligned frontier energy levels with a perovskite layer for efficient charge transfer/transport, showing a maximum power conversion efficiency (PCE) of 16.8%. Upon doping the PPDT2FBT HTL with a nonhygroscopic Lewis acid, tris(pentafluorophenyl)borane (BCF, 2–6 wt %), the vertical conductivity was improved by a factor of approximately 2, and the resulting PCE was further improved up to 17.7%, which is higher than that of standard PVSCs with 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as an HTL. After BCF doping, the clearly enhanced carrier diffusion coefficient, diffu...

Hole-transporting materials (HTMs) play a critical role in realizing efficient and stable perovskite solar cells (PVSCs). Considering their capability of enabling PVSCs with good device reproducibility and long-term stability, high-performance dopant-free small-molecule HTMs (SM-HTMs) are greatly desired. However, such dopant-free SM-HTMs are highly elusive, limiting the current record efficiencies of inverted PVSCs to around 19%. Here, two novel donor-acceptor-type SM-HTMs (MPA-BTI and MPA-BTTI) are devised, which synergistically integrate several design principles for high-performance HTMs, and exhibit comparable optoelectronic properties but distinct molecular configuration and film properties. Consequently, the dopant-free MPA-BTTI-based inverted PVSCs achieve a remarkable efficiency of 21.17% with negligible hysteresis and superior thermal stability and long-term stability under illumination, which breaks the long-time standing bottleneck in the development of dopant-free SM-HTMs for highly efficient inverted PVSCs. Such a breakthrough is attributed to the well-aligned energy levels, appropriate hole mobility, and most importantly, the excellent film morphology of the MPA-BTTI. The results underscore the effectiveness of the design tactics, providing a new avenue for developing high-performance dopant-free SM-HTMs in PVSCs.

Highly efficient nonfullerene polymer solar cells (PSCs) are developed based on two new phthalimide‐based polymers phthalimide‐difluorobenzothiadiazole (PhI‐ffBT) and fluorinated phthalimide‐ffBT (ffPhI‐ffBT). Compared to all high‐performance polymers reported, which are exclusively based on benzo[1,2‐b:4,5‐b′]dithiophene (BDT), both PhI‐ffBT and ffPhI‐ffBT are BDT‐free and feature a D‐A1‐D‐A2 type backbone. Incorporating a second acceptor unit difluorobenzothiadiazole leads to polymers with low‐lying highest occupied molecular orbital levels (≈−5.6 eV) and a complementary absorption with the narrow bandgap nonfullerene acceptor IT‐4F. Moreover, these BDT‐free polymers show substantially higher hole mobilities than BDT‐based polymers, which are beneficial to charge transport and extraction in solar cells. The PSCs containing difluorinated phthalimide‐based polymer ffPhI‐ffBT achieve a substantial PCE of 12.74% and a large V oc of 0.94 V, and the PSCs containing phthalimide‐based polymer PhI‐ffBT show a further increased PCE of 13.31% with a higher J sc of 19.41 mA cm−2 and a larger fill factor of 0.76. The 13.31% PCE is the highest value except the widely studied BDT‐based polymers and is also the highest among all benzothiadiazole‐based polymers. The results demonstrate that phthalimides are excellent building blocks for enabling donor polymers with the state‐of‐the‐art performance in nonfullerene PSCs and the BDT is not necessary for constructing such donor polymers.