Sx165

SAXS measurements were performed on the 4C and 9A beamlines at the Pohang accelator laboratory. X-ray beams with a wavelength of 0.735 Å and an energy resolution (ΔE/E) of approximately 2 × 10⁻⁴ were obtained from a double crystal monochromator with a Si(111) crystal at the Pohang Accelerator Laboratory (Pohang, Korea). Scattered X-ray intensities were measured by a 2-dimensional CCD camera (SX165, Rayonix; Evanston, IL USA). Sample cells with a thickness of 0.8 mm were used, and the windows on both sides were sealed with Kapton films. The sample-to-detector distance was 2 m, covering the q range of 0.012–0.17 Å⁻¹. The q range was calibrated using silver behenate [24 ].

X-ray diffraction was performed using MicroMax-007HF (Rigaku Corp.) equipped with rotating anode Mo-Kα (λ = 0.7093 Å) with multilayer optics (VariMax-Mo, Rigaku) and imaging plate (IP) detector (R-axis IV⁺⁺, Rigaku). X-ray generator was operated at 1.2 KW (50 kV, 24 mA), and X-ray beam size was reduced to 100 μm using pin-hole collimator. Sample to detector distance was about 120 mm, and typical exposure time was about 10 min. IPanalyzer v3.551 and Crystalclear v2.0 software were used to calibrate and process the 2D images. In the case of K-NAT, data were measured using synchrotron radiation at beamline 9A of Pohang light source (PLS). Experimental parameters were 20.07 KeV X-ray (λ = 0.6178 Å), 100 μm beam size, 15 sec of exposure time, and CCD detector (Rayonix SX165, 80 μm in pixel size) with S-to-D of 218.577 mm.

Two-dimensional scattering images recorded with a Rayonix SX165 detector were azimuthally averaged to give one-dimensional scattering patterns. The scattering angle θ was converted to momentum transfer q using the formula q=4π/λsin(θ/2), where λ=1.377 Å is the X-rays wavelength. Since the changes induced in the scattering patterns by optical photoexcitation account for less than a percent of the absolute signal, data were normalized30 (link) at 1.4±0.1 Å⁻¹ before calculating difference patterns with respect to the pattern measured at −100 ps. For a given time delay, each scattering difference is compared with the average difference and a simple reduced criterion is used to discard the differences that are too far away from the average one. In the formula above, I_i refers to the scattered intensity for a given time delay and q-bin, I_i is the scattered intensity averaged over all repetitions, and σ_i is the error bar on the experimentally measured intensity. The differences that satisfy the above criterion are then used to produce the averages difference patterns shown in the paper. This procedure usually rejects ~15–25% of the differences.

Grazing-incidence small-angle X-ray scattering (GISAXS) experiments were performed at the 9A beam-line at Pohang Accelerator Laboratory (PAL), Korea. The typical operating conditions were set at a wavelength of 1.112 Å and a sample-to-detector distance of 6.48 m. The incidence angle (α_i) was set at 0.080 to 0.140^o, which were below and above the critical angle (0.113^o) to probe the surface and entire film structures, respectively. 2D GISAXS patterns were recorded using a 2D detector (SX-165, Rayonix) positioned at the end of a vacuum guide tube with an exposure time of 10 s.
To examine the surface morphology of PS-b-PMMA films, atomic force microscopy (AFM; Dimension 3100, Veeco Digital Instrument Co.) was operated in a tapping mode. A standard silicon nitride probe was used at 3% offset below their resonance frequencies ranging from 250 to 350 kHz, where height and phase images were taken at a scanning speed of 7 μm/s. SEM images of dry-etched PS-b-PMMA films were measured with a field emission scanning electron microscope (FE-SEM; JSM-6701F, JEOL) under an accelerating voltage of 5.0 kV using a semi-in-lens detector. To enhance the phase contrast between the PS and PMMA blocks, asymmetric dry (or plasma) etching (VITA, Femto Sci.) mode was operated with an O₂/Ar (5/1 in volume ratio) gas mixture under an RF power of 100 W at 150 mTorr and 18 sccm.

The GIWAXS measurement was carried out with Pohang Accelerator Laboratory beamline using an In-Vacuum Undulator 20B source (11.08 keV) and a 2D CCD detector (Rayonix SX165, USA). The incidence angles were 0.08° (α_i < α_c) and 0.11°(α_i ~ α_c). The samples for GIWAXS measurements were fabricated on silicon substrates using the same recipe for the devices. NEXAFS experiments were detected by Scienta R3000 with 10¹¹ (photon/s) intensity from a bending magnet-type light source (beam size ~0.7 mm by 1.2 mm) and fully calibrated with Au 4f peak. Angle-resolved NEXAFS spectroscopy was conducted in total electron yield mode to collect the molecular orientation information from the uppermost (~10 nm) surface part of the PffBT4T-2DT thin films.

AFM images were acquired using a Bruker Dimension EDGE in tapping mode. The GIWAXS data was obtained from the PLS II 3C SAXS-I and 9A U-SAXS beamline of the Pohang Accelerator Laboratory in Korea. The active layer samples were deposited on the Si/PEDOT:PSS substrates following device conditions. The X-rays coming from the in-vacuum undulator (IVU) were monochromated (wavelength λ = 1.10994 Å) using a double crystal monochromated and focused both horizontally and vertically (100 (H) × 20 (V) μm² in FWHM @ the sample position) using K-B type mirrors. The grazing incidence wide-angle X-ray scattering sample stage was equipped with a 7-axis motorized stage for the fine alignment of the sample, and the incidence angles of the X-beam was set to be 0.11°–0.13°. The GIWAXS patterns were recorded with a 2D CCD detector (Rayonix SX165) and an X-ray irradiation time within 100 s, dependent on the saturation level of the detector. Diffraction angles were calibrated using a sucrose standard (monoclinic, P21, a = 10.8631 Å, b = 8.7044 Å, c = 7.7624 Å, and β = 102.938°) and sample-to-detector distance was ~231 mm. The GISAXS measurements were performed with a Xeuss 2.0 SAXS/WAXS laboratory beamline using a Cu X-ray source (8.05 keV, 1.54 Å) and a Pilatus3R 300 K detector.