Device Fabrication. ITO glass substrates were cleaned in acetone, detergent, deionised (DI) water, and ethanol using ultrasonic treatment for 20 min, respectively. After 20 min of ozone plasma treatment, a 40 nm-thick TiO2 layer was spin-coated on the ITO substrates using the colloidal TiO2 solution (2500 rpm, for 35s), followed by annealing at 150 °C for 30 min in ambient air. This process was repeated twice. Then, Pb/Sn metals with different thicknesses were thermally evaporated on the TiO2-coated ITO glasses. The alloy composition was controlled by the thickness of Tin and Lead films. Subsequently the substrates with metal or alloy films were transferred into a tubular CVD furnace (1 inch quartz tube) and placed into two small quartz containers at the center of tube close to the thermocouple. The MAI powder was spread inside the small tube beside the substrates. Thereafter, the reaction between MAI and Pb/Sn-coated substrates was performed at 185 °C for 40 min under continuous Argon flow at a rate of 100 standard cubic centimetres per minute (SCCM)). After completion of the reaction, the samples were transferred into a nitrogen glovebox. Then, the surface of perovskite film was treated with isopropanol (IPA) using spin coating at 4000 rpm for 30 s. In order to complete the device, spiro-OMeTAD (Lumtec, Taiwan) solution (80 mg/1mL chlorobenzene) containing 17.5 µl Li-bis(trifluoromethanesulfonyl) imide (Li-TFSI)/acetonitrile (500 mg/1 ml) and 28.5 µl TBP was spin coated onto the perovskite film at 4000 rpm for 20 s, followed by thermal evaporation of 100 nm-thick gold as an electrode. The active area of device was 0.1 cm2.
Device Fabrication. The devices used in this study were constructed by conventional soft lithographic techniques.24 Briefly, a master was prepared from SU-8 2025 (Microchem Corp.) on a silicon wafer (Compart Technology Ltd.). Slygard 184 (Dow Corning) was mixed in a 10:1 (w/w) ratio of resin to cross-linker and then poured over the master. A thickness of 50 μm was achieved by adjusting the spin coater velocities in two spinning phases: an initial phase with 500 rpm for 5 s at an acceleration of 300 rpm/s and a later phase with 1650 rpm for 40 s at 300 rpm/s. After degassing, the device was cured for 6 h at 65 °C, and the poly(dimethylsiloxane) (PDMS) was cut and peeled off the master. Access holes for the tubing and for the electrodes were drilled with a biopsy punch, and the device (total length approximately 5 cm) was exposed to air plasma for 30 s (Femto Xxxxxx) and sealed onto a standard microscope glass slide (Agar Scientific). The channels were then rendered hydrophobic by baking at 65 °C for 10-12 h before use. Electrodes were fabricated afterwards by placing the device on a hot plate and heating to 130 °C. Low melting point solder wire (No. 19, Indalloy) was pushed by hand into the entrance hole. The solder melted on contact with the hot glass and filled the void space up to the exit hole. In order to facilitate contact with the electrical equipment, copper wire was inserted into the molten solder at the entrance hole. The device was left to cool to room temperature before use. Polyethylene tubing (internal diameter i.d. = 0.38 mm, Xxxxxx Xxxxxxxxx) for delivery of the liquid phases was connected to glass syringes (Xxxxxxxx) and the other end was inserted into the device relying on the elastic properties of PDMS to form a seal. Device Operation. The fluid flow was driven by syringe pumps (Harvard Apparatus PhD 2000 infusion). Light mineral oil (Sigma Xxxxxxx) containing 2% (w/w) Span80 (Fluka) as a surfactant was B xx.xxx.xxx/00.0000/xx000000x |Anal. Chem. XXXX, XXX, 000–000 Figure 2. Complex formation triggered by electrocoalescence. The traps (Figure 1) are populated with two droplets. The contents of these droplets are randomly distributed, with about half of all droplet pairs containing the two different reactants for complex formation. The lighter colored solution in the lower droplet is KSCN (0.8 M) and the darker solution is Fe(NO3)3 (0.27 M). Upon application of an electric field the droplets merge, leading to the formation of a dark complex (FeSCN3). The red ...
Device Fabrication. The fabrication process begins with a commercial semi-insulating GaAs wafer containing six periods of upper and lower Xxxxx layers. The Xxxxx stack is composed of alternative 127 nm high (Al0.28Ga0.72As) and 622 nm low (Al0.72Ga0.28As) index materials, which are grown using molecular beam epitaxy. The core layer (Al0.17Ga0.83As) with a thickness of 230 nm is sandwiched between the Xxxxx layers. The device fabrication proceeds as follows: First, a 1μm thickness SiO2 is deposited using plasma-enhanced chemical vapor deposition. Next, a layer of photoresist is applied onto the wafer, and the waveguide pattern is defined by lithography along GaAs crystal orientation [110]. Following that, the SiO2 is etched away in a reactive ion etching step using fluorine gas, with the patterned photoresist serving as the etching mask. After that, the ridge waveguide is fabricated by dry-etching using chlorine gas. Finally, the sample is cut along the cleavage plane with smooth edges.
Device Fabrication. The electron donor material (P3HT or F8TBT) was spin-cast on PEDOT:PSS coated ITO/glass or PET substrates, while the electron acceptor material (PCBM) was deposited on a Si sub- strate or a Kapton film coated with a thermally evaporated Al cathode. Since P3HT is easily oxidized and decomposes at ele- vated temperatures (usually above 60 °C) and PCBM is difficult to imprint by thermal embossing under mild conditions due to its very high melting point, we employed solvent assisted nanoimprint lithography (XXXXX)[20], which provides a way to pattern polymer films at room temperature and quite low pres- sure of only several millibars. The XXXXX conditions, especially the solvent vapor saturation and swelling time, were carefully optimized to ensure that residual layers were still present in the patterned films to avoid shorting the devices. In summary, the imprinted P3HT:PCBM devices were fabricated by using XXXXX twice, while F8TBT:PCBM devices were imprinted using XXXXX and conventional NIL to pattern PCBM and F8TBT, respectively. The order of the two imprinting steps using the same Si molds for P3HT:PCBM and F8TBT:PCBM devices was different (Figure 1), because of the varying imprinting require- ments of different materials and the volume ratio of pillar and hole arrays. Details of these can be found in the experimental part. In order to perform a systematic study of the correlation of device performance with feature size and interface area, a series of molds were either fabricated in-house using e-beam lithography or were obtained commercially from NIL Tech- nology ApS. The molds contain 75–80 nm deep 2-D dot pat- terns with feature sizes of 200, 150, 100, 80, 40, and 25 nm and equivalent spacing (i.e., the pitch is double the feature size) and with patterned area of 4 mm × 2 mm for each pixel. In addi- tion, for some experiments two types of 1-D grating patterns were also used, one with 50 nm wide lines separated by 50 nm gaps, the other with 20 nm wide lines separated by 80 nm gaps. Two types of control cells based on planar bilayers (by non- patterned double imprinting) and standard blend films (by spin-coating from a mixture solution), for both F8TBT:PCBM and P3HT:PCBM systems, were fabricated for comparison. Fab- rication procedures are detailed in the Experimental Section. xxx.XxxxxxxxxXxxxx.xxx Figure 2. AFM (a1–b2, d1–d3) and SEM (c1, c2) images of double imprinted films. Plan-view AFM images of the (a1) P3HT – (a2) PCBM pair showing an grid of 100 ...
Device Fabrication. FTO glasses (NSG-10) were chemically etched using zinc powder and HCl solution (2 M), followed by four steps ultrasonic cleaning using Triton X100 (1 vol% in deionized water), DI water, acetone, and ethanol, respectively. All substrates were further cleaned by ozone plasma for 15 min, before deposition of each EEL. To prepare TiO2 compact layer, a precursor solution of titanium diisopropoxide (Sigma-Xxxxxxx) in ethanol was deposited on the substrates at 450 °C using spray pyrolysis process, followed by 30 min annealing at 450 °C. Thereafter, a 150 nm-thick mesoporous TiO2 was spin coated on compact TiO2 (4000 rpm for 15 s with a ramp rate of 2000 rpm/s) from a diluted TiO2 paste (Dyesol 30 NR-D) in ethanol, followed by annealing the substrates at 450 °C for 30 min. To modify the surface of mp-TiO2, SnO2 precursor solution (0.1 M SnCl2.2H2O in ethanol) was spin-coated on top of mp-TiO2 with a 20 s delay time to allow for full impregnation before spinning at 6000 rpm for 40 s. Subsequently, the film was annealed at 180 °C for 1 hour. We converted the a-SnO2 to crystalline phase (c-SnO2) by annealing the film at 450 °C for 1 hour. The SnO2 quantum dots (SnO2-NC) had a size of 3-5 nm and were deposited on top of the mp-TiO2 by spin coating at 5000 rpm for 20 s with 2000 rpm/s ramp-rate, followed by annealing at 150 °C for 1 hour. For deposition of perovskite film a precursor solution of (FAPbI3)0.87(MAPbBr3)0.13was first prepared by mixing FAI (1.05 M, Dyesol), PbI2 (1.10 M, TCI), MABr (0.185 M, Dyesol) and PbBr2 (0.185 M, TCI) in a mixed solvent of DMF:DMSO = 4:1 (volume ratio). Then, a 5 vol% of 1.5 M CsI solution in DMSO was added into the perovskite solution in order to have a triple cation perovskite. The solution was spin-coated at 1000 rpm for 10 s and, continuously at 4000 rpm for 30 s. During the second phase, 200 μL of chlorobenzene was dropped on top of the film 10 s before end of spinning. Thereafter, the film was annealed first at 120 °C for 10 min followed by 40 min at 100 °C. After annealing and cooling the samples, spiro-OMeTAD solution in chlorobenzene (70 mM) containing a solution bis(trifluoromethylsulfonyl)imide lithium salt (Li- TFSI, Sigma-Xxxxxxx) in acetonitrile (200 mg/400 µL) and (4-tert-butylpyridine-Sigma-Xxxxxxx) with molar ratios of 0.5 and 3.3, respectively, was prepared and spin-coated at 4000 rpm for 20 s (using a ramp rate of 2000 rpm/s). Finally, 80-nm thick gold was thermally evaporated as a back contact to complete the devi...
Device Fabrication. The proposed program will apply the film synthesis techniques described above to make simple piezoelectric thin film devices using facilities in the Atwater lab and also the Micro/Nano Fabrication Lab, a newly created laboratory for microfabrication and nanofabrication located on the first floor of Xxxxxx Laboratory at Caltech. These laboratories have conventional optical lithography with a 1.5 µm resolution mask aligner suitable for up to 3” substrates, positive photoresist processing, wet chemical etching, CVD for silicon nitride and silicon dioxide, metal evaporation, polymer layer fabrication, optical inspection and metal thin film evaporation. Device characterization by I-V, C-V, Hall mobility and carrier density and spreading resistance can be performed from 25-150 C. An electrical measurement probe station is available for current-voltage and capacitance voltage characterization using Xxxxxxxx Instruments ICS-based 236 source-measurement units. Surface profilometry and piezoresponse force microscopy is available using a Thermomicroscope AutoProbe CF atomic force microscope.
