Polymeric sheets were perforated by laser ablation and were uncompromised by a debris field when first treated with a thin layer of photoresist. Polymer sheets perforated with holes comprising 5, 10, and 20% of the nominal surface area were then patterned in stripes by photolithography, which was followed by synthesis in exposed regions of a cell-attractive zirconium oxide-1,4-butanediphosphonic acid interface. Microscopic and scanning electron microscopy analyses following removal of unexposed photoresist show well-aligned stripes for all levels of these perforations. NIH 3T3 fibroblasts plated on each of these perforated surfaces attached to the interface and spread in alignment with pattern fidelity in every case that is as high as that measured on a nonperforated, patterned substrate.Keywords: perforated substrate; polymer laser ablation; two-dimensional patterned cell alignment;

The classical SiO2/Si interface, which is the basis of integrated circuit technology, is prepared by thermal oxidation followed by high temperature (>800 °C) annealing. Here we show that an interface synthesized between titanium dioxide (TiO2) and hydrogen-terminated silicon (H:Si) is a highly efficient solar cell heterojunction that can be prepared under typical laboratory conditions from a simple organometallic precursor. A thin film of TiO2 is grown on the surface of H:Si through a sequence of vapor deposition of titanium tetra(tert-butoxide) (1) and heating to 100 °C. The TiO2 film serves as a hole-blocking layer in a TiO2/Si heterojunction solar cell. Further heating to 250 °C and then treating with a dilute solution of 1 yields a hole surface recombination velocity of 16 cm/s, which is comparable to the best values reported for the classical SiO2/Si interface. The outstanding performance of this heterojunction is attributed to Si–O–Ti bonding at the TiO2/Si interface, which was probed by angle-resolved X-ray photoelectron spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) showed that Si–H bonds remain even after annealing at 250 °C. The ease and scalability of the synthetic route employed and the quality of the interface it provides suggest that this surface chemistry has the potential to enable fundamentally new, efficient silicon solar cell devices.

A nanometer thick, micron scale-patterned interface on a polymeric material directs fibroblast proliferation into a highly aligned, confluent cell monolayer. These cells assemble fibronectin extracellular matrix (ECM) fibrils that are aligned with the pattern, and matrix alignment on the synthetic polymer surface is maintained throughout a decellularization process. Biologic relevance of this ECM-synthetic material composite is illustrated by directing oriented neurite outgrowth in register with the aligned matrix fibrils.

The first example of systematic control of the work function of a conducting polymer is illustrated for PEDOT:PSS. A nanometer-thick film of TiO2 is formed on the PEDOT:PSS surface and forms an adhesion layer to bond phosphonic acids to the polymer; the work function of the PEDOT:PSS (ΦPEDOT:PSS) is adjusted by choice of phosphonic acid over a range of approximately 0.8 eV, and ΔΦPEDOT:PSS correlates strongly with the calculated gas-phase dipole moments of the phosphonates.Graphical abstractHighlights► A nanometer thick adhesion layer can be synthesized on the surface of a conducting polymer. ► Self-assembled monolayers of phosphonates can be formed on this adhesion layer. ► The dipole moments of the phosphonates can be manipulated to control the work function of the conducting polymer. ► Ultraviolet photoelectron spectroscopic analysis supports Kelvin probe measurements of work function changes.

The first quantitative comparison between self-assembled monolayers of homologous carboxylate- and phosphonate-terminated organic dyes that are of use in dye-sensitized solar cells (DSSCs) is reported. (Cyanovinyl)phosphonate-terminated oligothiophenes and (cyanovinyl)carboxylate-terminated oligothiophenes were synthesized on TiO2 thin film electrodes. Structurally analogous organics were compared for the effect of the anchoring groups on photochemical properties in solution as measured by UV/vis spectroscopy and for reactivity with the electrode surface. Monolayers were grown on the TiO2 electrodes either by “tethering by aggregation and growth” (T-BAG) or by solution dipping. Surface roughness and homogeneity, elemental composition, and thickness of the monolayers were evaluated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and ellipsometry. Molecular loadings for each monolayer on TiO2 were quantified by quartz crystal microgravimetry (QCM), and the stability of bonding between each class of dyes and the TiO2 was evaluated by measuring desorption, also by QCM; the carboxylates underwent significant dissociation in aqueous media but the phosphonates did not. DSSCs were prepared from each congener and from simple oligothiophene phosphonates to determine the effect of the cyanovinyl group on device behavior; all DSSCs were studied under irradiation from a AM 1.5G solar light source; the effect of cyanovinyl group termination was comparable to that of adding a thiophene moiety, and the DSSC using a self-assembled monolayer of (sexithiophene)phosphonate (6TP) had total power conversion efficiency (η) of ca. 5%.Keywords: carboxylate self-assembled monolayers; dye-sensitized solar cells; oligothiophenes; phosphonate self-assembled monolayers; precious metal-free dye;

A novel interface was prepared on glass slides that stabilizes several cast polymers against delamination under conditions necessary for the study of cell surface interactions. This interface was synthesized by deposition of zirconium tetra(tert-butoxide) from the vapor phase onto the glass followed by mild thermolysis, which gives a surface-bound zirconium oxide coating. This oxide coating improved attachment of polymer coatings cast from formic acid or methylene chloride. Nylon, polyurethane, and polyhydroxybutyrate/polyhydroxyvalerate coatings were stable against delamination from the oxide-coated glass following sonication in ethanol for more than 30 min or immersion in water at pH 8 for at least 48 h.Keywords: delamination inhibition; glass surface modification; polymer casting; polymer−glass interface

Seeding polymer substrates for the attachment and growth of metallic contacts is an important problem in modern microcircuit fabrication. A new method to effect such polymer metallization is described in which the polymer is first treated with vapor of zirconium or titanium tetra-tert-butoxide and then thermalyzed to give several monolayers of zirconium or titanium oxides that are attached to the polymer surfaces. The thickness of this layer can be controlled by the vapor exposure time. The thin oxide layers withstand removal by strenuous flexing of the polymers, and they absorb copper sulfate from an aqueous solution. Upon simple treatment with dialkylaminoborane or sodium borohydride, the polymer is metallized with copper. The tetra-tert-butoxides can be deposited through a mask, and patterned metallization of the polymers is easily accomplished.Keywords: adhesion layer; polymer metallization

A nanometer thick, micron scale-patterned interface on a polymeric material directs fibroblast proliferation into a highly aligned, confluent cell monolayer. These cells assemble fibronectin extracellular matrix (ECM) fibrils that are aligned with the pattern, and matrix alignment on the synthetic polymer surface is maintained throughout a decellularization process. Biologic relevance of this ECM-synthetic material composite is illustrated by directing oriented neurite outgrowth in register with the aligned matrix fibrils.