Revisiting the Charge-Transfer States at Pentacene/C60 Interfaces with the GW/Bethe–Salpeter Equation Approach

Molecular orientations and interfacial morphologies have critical effects on the electronic states of donor/acceptor interfaces and thus on the performance of organic photovoltaic devices. In this study, we explore the energy levels and charge-transfer states at the organic donor/acceptor interfaces on the basis of the fragment-based GW and Bethe–Salpeter equation approach. The face-on and edge-on orientations of pentacene/C60 bilayer heterojunctions have employed as model systems. GW+Bethe–Salpeter equation calculations were performed for the local interface structures in the face-on and edge-on bilayer heterojunctions, which contain approximately 2000 atoms. Calculated energy levels and charge-transfer state absorption spectra are in reasonable agreements with those obtained from experimental measurements. We found that the dependence of the energy levels on interfacial morphology is predominantly determined by the electrostatic contribution of polarization energy, while the effects of induction contribution in the edge-on interface are similar to those in the face-on. Moreover, the delocalized charge-transfer states contribute to the main absorption peak in the edge-on interface, while the face-on interface features relatively localized charge-transfer states in the main absorption peak. The impact of the interfacial morphologies on the polarization and charge delocalization effects is analyzed in detail.

Sintesis Komposit TiO2-Bentonit dan Aplikasinya untuk Penurunan BOD dan COD Air Embung UNNES

Abstrak Telah disintesis komposit TiO2-bentonit untuk penurunan BOD dan COD. Penelitian ini bertujuan untuk mengetahui proses pembentukan komposit TiO2-Bentonit serta mengetahui katalis terbaik dalam proses fotodegradasi air embung. Penelitian diawali dengan preparasi TiO2-Bentonit. Hasil pembentukan komposit dikarakterisasi dengan menggunakan X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) dan Scanning Electron Microscope (SEM). Katalis yang diuji adalah TiO2, bentonit, TiO2-bentonit yang diaplikasikan ke air embung dengan waktu penyinaran selama 30 menit.Terbentuknya komposit TiO2-Bentonit ditunjukkan dengan refleksi TiO2 pada 2 25. Hasil analisis menggunakan FTIR yakni Ti-O antara range 400-700 cm -1 dalam hal ini ditunjukkan dalam peak 478.35 dan 594.08. Puncak serapan-serapan utama pada bentonit beradi di bilangan gelombang 3626.17 cm-1, 3448.72 cm-1 dan 1635.64 cm-1. Spektra TiO2-Bentonit tidak menunjukkan adanya pergeseran serapan pada bilangan gelombang 3448.72 cm-1 yang belum menunjukkan ikatan O-H yang semakin lemah karena adanya TiO2 di dalam antar lapis bentonit.Penurunan nilai BOD dan COD terbesar diperoleh dengan menggunakan TiO2-Bentonit yakni untuk BOD 18.40 ppm dan COD 10.05ppm. Kemampuan komposit TiO2-Bentonit lebih besar dibandingkan katalis TiO2 dan bentonit. Kata kunci: air embung, fotodegradasi, TiO2-bentonit Abstract Have done synthesized composite TiO2-bentonite to decrease BOD and COD. This study aims to determine the process of form he composite TiO2-bentonite and determine the best catalyst in the process of photodegradation water reservoir. The study begins with the preparation of TiO2-bentonite. Results composite formation characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The catalyst is tested TiO2, bentonite, TiO2-bentonite which is applied to the water reservoir with the exposure time for 30 menit.Terbentuknya composite TiO2-bentonite indicated by TiO2 reflection on the 2θ ≥ 25. FTIR analysis results using the Ti-O between the range 400-700 cm-1 in this case is shown in peak 478.35 and 594.08. The main absorption peak-absorption on bentonite beradi at wavenumber 3626.17 cm-1, 3448.72 and 1635.64 cm-1. TiO2-bentonite spectra did not indicate any shift in absorption at wavenumber 3448.72 cm-1 which has not shown the OH bond is weakened by the existence of TiO2 in between layers of bentonite. Impairment The BOD and COD obtained using the TiO2-bentonite for BOD 18.40 ppm and 10.05 ppm COD. TiO2-bentonite composite capability greater than TiO2 catalyst and bentonite. Keyword: air embung, photodegradation, TiO2-bentonite DOI: http://dx.doi.org/10.15408/jkv.v0i0.3620

Surface Morphology and Optical Property of Silver Nanoparticle Thin Film Prepared by Electrostatic Spray Deposition

Silver nanoparticle thin films were deposited on glass substrates by electrostatics spray deposition. Electrostatic spray condition was optimized by varying distance between nozzle and substrate between 20 mm and 60 mm, deposition time was fixed at 5 minute. The surface morphology and optical properties of films were carried out by using Atomic Force Microscope (AFM), Field Emission Scanning Electron Microscopy (FE-SEM) and UV-Vis Spectrophotometer. The results is indicate that the surface morphology of silver nanoparticle thin film show the grain size of film near around 100 nm at distance between nozzle and substrate of 60 mm and the RMS roughness decreases from 9.59 nm to 2.35 nm when distance between nozzle and substrate was increased from 20 mm to 60 mm. The optical absorption spectra showed the main absorption peak at 436 nm. When the distance between the nozzle and the substrate raise, decrease in absorption has been observed.

FAR-INFRARED MAGNETO-OPTICAL STUDY ON ZnSe LAYERS

We report on a study of the far-infrared (FIR) magneto-absorption of ZnSe layers epitaxially grown on GaAs by metal-organic vapor-phase epitaxy (MOVPE) or molecular-beam epitaxy (MBE). The Zeeman absorption of the residual donors is observed in undoped and p -type ZnSe layers. A main absorption peak is assigned to a 1s to 2p+ transition of an electron bound to a Cl donor. Polaron pinning effect is included to explain the peak position within the framework of Wigner–Brillouin second order perturbation theory.