CuPC-applied perovskite solar cells show excellent long-term thermal stability which is attributed to the reliable interface and intrinsic heat-resistance of CuPC.

In this paper, an electron donor-acceptor (D-A) substituted dipolar chromophore (BTPA-TCNE) is developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar cells (PVSCs). BTPA-TCNE is synthesized via a simple reaction between a triphenylamine-based Michler's base and tetracyanoethylene. This chromophore possesses a zwitterionic resonance structure in the ground state, as evidenced by X-ray crystallography and transient absorption spectroscopies. Moreover, BTPA-TCNE shows an antiparallel molecular packing (i.e., centrosymmetric dimers) in its crystalline state, which cancels out its overall molecular dipole moment to facilitate charge transport. As a result, BTPA-TCNE can be employed as an effective dopant-free HTM to realize an efficient (PCE ≈ 17.0%) PVSC in the conventional n-i-p configuration, outperforming the control device with doped spiro-OMeTAD HTM.

We have successfully utilized epoxyisophorone ring-opening chemistry to efficiently incorporate the butylthio group to the phenyltetraene bridge of highly efficient nonlinear optical chromophores in high overall yield. By following the guidance of Dewar’s rules, the sulfur atom functions as a moderate π-accepting group at a starred position of the conjugated bridge. Several of very critical material parameters of the phenyltetraenic chromophores for device applications have been intrinsically and simultaneously improved through such a simple and straightforward engineering of molecular structures. Compared with the nonsubstituted analogue 2, thiolated chromophore 1 achieves higher molecular hyperpolarizability (34%), enhanced E-O coefficient (38%), significantly improved photochemical stability against 1O2 (by an order of magnitude), and better optical transparency (17 nm blue-shifted λmax absorption spectrum).

Recent progress in developing highly efficient nonlinear optical dendrimers and polymers for high-performance electro-optic (EO) devices has been reviewed. Our efforts are focused on using nanoscale architectural control to tailor the size, shape, conformation, and functionality of NLO chromophores and macromolecules and studying their effects on poling efficiency. The structures of these materials vary from a 3-D-shaped dendritic chromophore, multifunctional dendrimers with the center core connected to NLO chromophores and cross-linkable functional groups at the periphery, to side-chain-dendronized NLO polymers. All the poling results from these systems have shown dramatically enhanced EO properties (a factor of 2−3) compared to conventional NLO polymers.

Three amphiphilic block copolymers are employed to form polymeric micelles and function as nanocarriers to disperse hydrophobic aggregation‐induced emission (AIE) dyes, 1,1,2,3,4,5‐hexaphenylsilole (HPS) and/or bis(4‐(N‐(1‐naphthyl) phenylamino)‐phenyl)fumaronitrile (NPAFN), into aqueous solution for biological studies. Compared to their virtually non‐emissive properties in organic solutions, the fluorescence intensity of these AIE dyes has increased significantly due to the spatial confinement that restricts intramolecular rotation of these dyes and their better compatibility in the hydrophobic core of polymeric micelles. The effect of the chemical structure of micelle cores on the photophysical properties of AIE dyes are investigated, and the fluorescence resonance energy transfer (FRET) from the green‐emitting donor (HPS) to the red‐emitting acceptor (NPAFN) is explored by co‐encapsulating this FRET pair in the same micelle core. The highest fluorescence quantum yield (∼62%) could be achieved by encapsulating HPS aggregates in the micelles. Efficient energy transfer (>99%) and high amplification of emission (as high as 8 times) from the NPAFN acceptor could also be achieved by spatially confining the HPS/NPAFN FRET pair in the hydrophobic core of polymeric micelles. These micelles could be successfully internalized into the RAW 264.7 cells to demonstrate high‐quality fluorescent images and cell viability due to improved quantum yield and reduced cytotoxicity.

Polymeric micelles are promising carriers for anticancer agents due to their small size, ease of assembly, and versatility for functionalization. A current challenge in the use of polymeric micelles is the sensitive balance that must be achieved between stability during prolonged blood circulation and release of active drug at the tumor site. Stimuli-responsive materials provide a mechanism for triggered drug release in the acidic tumor and intracellular microenvironments. In this work, we synthesized a series of dual pH- and temperature-responsive block copolymers containing a poly(ε-caprolactone) (PCL) hydrophobic block with a poly(triethylene glycol) block that were copolymerized with an amino acid-functionalized monomer. The block copolymers formed micellar structures in aqueous solutions. An optimized polymer that was functionalized with 6-aminocaproic acid (ACA) possessed pH-sensitive phase transitions at mildly acidic pH and body temperature. Doxorubicin-loaded micelles formed from these polymers were stable at blood pH (~7.4) and showed increased drug release at acidic pH. In addition, these micelles displayed more potent anti-cancer activity than free doxorubicin when tested in a tumor xenograft model in mice.

Poled electro-optic (EO) polymers have enabled many advances in the exploration of high-speed and broadband information technologies.[1] Polymer based EO devices have been demonstrated to have large bandwidths (over 110 GHz), low driving voltages, and sustain their performance in a flexible form [2] or under extreme environmental conditions. [3,4] For optical circuits, EO polymers can be easily integrated with stripline-or ring-structured waveguides made of sol-gels, [5] low-loss fluorinated polymers, [6] silicon slots, [7] conducting oxides, [8] and photonic crystals. [9] Recently, EO polymers have also been utilized for the generation/detection of a gap-free pulsed THz system with a bandwidth up to ca. 12 THz.[10]Large numbers of discrete photonic components need to be inserted into integrated systems of telecommunication and silicon microphotonics, especially where an extreme amount of data is required to travel in a very small space.[11] Therein lies the great challenge for polymer-based EO technologies: to have thermally stable EO coefficients (r 33 ) of around 500 pm V -1 at wavelengths of 1.31 or 1.55 lm.[11b]Currently, the most commonly used materials for polymeric EO devices are based on poled polymers with r 33 values around 50-80 pm V -1 at wavelengths of 1.31 or 1.55 lm. In these materials, dipolar nonlinear optical (NLO) chromophores have been doped or incorporated at a level of ca. 20-25 wt % to reach their maximum r 33 values. [5][6][7][8][9][10] Beyond such a moderate loading of chromophores, strong intermolecular electrostatic interactions severely limit the poling-induced polar order and cause phase-separation problems between chromophores and polymers.To further improve EO activity, research efforts have focused on developing shape-engineered chromophores with high molecular optical nonlinearities (lb), [12] where lb is a product of first hyperpolarizability and the dipole moment of the NLO chromophore, and increasing order within the matrices by controlling the nanoscale architecture of macromolecules. [13] In our recent study we have demonstrated, using Diels-Alder (DA) "click chemistry" to post-functionalize NLO chromophores onto polymers, that high chromophore loading levels (up to 35 wt %) and large r 33 values (up to 110 pm V -1 ) could be achieved in in situ generated side-chain dendronized NLO polymers with non-reacted chromophores as guest dopants. [14] This opens a new avenue to explore optimal host-guest combinations and to develop an efficient way to control lattice hardening in these hybrid polymers. The ultimate goal is to simultaneously achieve very large EO activity, good thermal stability, high optical transparency, and excellent mechanical properties within the same material via molecular design and facile processing. In this paper, we report a novel method to disperse a highly efficient secondary chromophore into in situ crosslinked NLO polymer networks, leading to both enhanced EO activity (> 260 pm V -1 at 1.31 lm) and alignment stability at 85°C. In photorefractive (PR) po...

can be independently adjusted. Shown in Figure 3e is one example of using a size-reduced nanopillar for nanoimprinting. In this case, the size of nanopillars was reduced using a chromium etchant. The lateral dimension of the imprinted holes was less than 30 nm. Other approaches to size reduction are currently under investigation in our group.In summary, we have developed a low-cost, high-throughput fabrication process for producing large-area, well-ordered periodic nanopillars for nanoimprinting with feature size less than 50 nm that would allow the nanoimprinting technique to be easily accessed without the need for e-beam lithography. When these stamps are used in nanoimprint lithography, large-area periodic nanostructures with lateral dimensions less than 30 nm can be obtained. The size and separation of the fabricated periodic nanostructures can be independently adjusted by selecting different diameters of polystyrene beads in the nanosphere lithography step and by trimming the nanopillars using various size reduction techniques, respectively. The shape of the nanostructures can also be modified by using different combinations of metal masks and etching recipes. ExperimentalNanopillars: To fabricate silicon nanopillars, 1 1 cm 2 substrates cut from ndoped silicon (100) wafers (Gredmann) were used. These silicon substrates were cleaned by immersion in piranha solution (3:1 concentrated H 2 SO 4 / 30 % H 2 O 2 ) and sonication for 30 min. After sonication the substrates were rinsed repeatedly with ultrapure water (18.2 MX, Millipore Simplicity), acetone, and methanol and used immediately. To produce metal masks for the nanopillar array, nanosphere lithography was employed. Details of the nanosphere lithography procedure can be found in the literature [21,22]. In short, monodispersed polystyrene beads of various diameter purchased from Bangs Laboratories, Inc. (Fishers, IN) were diluted in a solution of surfactant Triton X-100 (Aldrich) and methanol (1:400 by volume). This solution was then spin-cast onto substrates to form hexagonally closed-packed 2D colloidal crystals. Depending on the experimental requirements (single or double layer), the speed of spin-coater was varied between 800 and 3600 rpm (~1500 rpm for a double layer), and the dilution ratio of the polystyrene solution was also changed. It was found that the formation of self-assembled 2D colloidal crystals strongly depended on the speed of spin-coater. These 2D colloidal crystals were then used as the deposition templates. A 50 nm thick Cr film was deposited over the polystyrene masks at a rate of 15 nm min ±1 in an ULVAC vapor deposition system at a pressure of 1 10 ±3 Pa. After Cr deposition, the polystyrene beads were removed by sonicating the substrates in CH 2 Cl 2 solution for 3±5 min. To fabricate silicon nanopillar arrays, substrates with metallic masks were placed in a reactive ion etcher (Oxford Plasmalab 80 Plus, 80 W) with a gas mixture of CHF 3 (20 sccm) and O 2 (2 sccm) at a total pressure of 25 mtorr. The nanopillars used for nanoimpri...