Improving the Stability of High and Low Bandgap Polymers Organic Photovoltaic Devices Using a Solution Based Titanium Sub-Oxide Interfacial Layer

The improvement in device efficiency has brought organic photovoltaic (OPV) devices closer to commercial viability, highlighting the importance of studying the lifetime and stability of OPV devices. At present, the lifetime and stability of OPV devices is much shorter and poor mainly caused by oxygen, moisture, and light resulting in the oxidation on low work function electrodes and the degradation of the morphology of the photoactive layer. To improve the lifetime and stability of the OPV devices, we used newly developed low bandgap polymer, PCDTBT, as the electron acceptor material and a solution based titanium sub-oxide (TiOx) interfacial layer inserted between the active layer and the cathode. In our experiment, we fabricated unencapsulated bulk heterojunctions OPV devices based on the high and low bandgap polymers of P3HT:PC61BM and PCDTBT:PC71BM, respectively. We synthesized a solution based TiOx by using a sol-gel chemistry method. We performed stability tests on the OPV devices: (1) with and without the TiOx layer (Case (I)) to test the effectiveness of the TiOx layer in protecting the photoactive layer from degradation, (2) with and without a protection cover (a high research grade opaque Al foil) to observe the device performance in a dark/light environment (Case (II)), and (3) in different storage media conditions: (a) air, (b) glove box, (3) ante-chamber of a glove box, and (4) (Case (III)). We spent significant time and effort in optimizing the fabrication processing steps including; the thickness of the active layer, pre-annealing and post-annealing treatments. We fabricated the OPV devices by using the optimal fabrication procedure. We found that the best PCE value of 4.1% achieved for the P3HT:PC61BM OPV cell and 5.1% for the PCDTBT:PC71BM OPV cell. On the air stability test, we found that the OPV cell of P3HT:PC61BM materials showed good air stability performance resulting in the PCE only dropping 26% over a period of 70 days (stored in a glove box). The PCDTBT:PC71BM devices stored in the glove box over a period of 30 days showed relatively good air stability performances; (1) the device with a TiOx, layer and an opaque Al cover the PCE dropped only 16%, (2) the device with the TiOx layer and without an opaque Al cover PCE dropped 34%, and (3) the device without a TiO x, layer and with an Al cover PCE dropped 48%. While the PCDTBT:PC71BM devices stored in the air; (1-2) with a TiOx layer and with/without opaque Al covers the PCE values dropped 92% after 18 days, and (3) without the TiOx, layer and with an opaque Al cover, the PCE dropped 100% after 3 days. These results highlight the effectiveness of the TiOx layer in protecting the active layer from degradation. We concluded that the TiOx, layer effectively improved the stability the OPV devices

Stability of High Band Gap P3HT: PCBM Organic Solar Cells Using TiOx Interfacial Layer

We fabricated a poly [3-hexylthiophene] (P3HT) and [6,6] -phenyl-C61-butyric acid methyl ester (PC61BM with the TiOx layer. We found that a solution based TiOx coated at a spin speed of 3000 rpm improved the photon absorption of the active layer. An optimized TiOx layer was also used as the interfacial layer to investigate the stability of P3HT: PC61BM OPC. After 70 days of storage, we observed that the short-circuit current density (JSC) dropped by 16.2%, fill factor (FF) dropped by 10.6%, and power conversion efficiency (PCE) dropped approximately by 25%, while the open-circuit voltage (VOC) remained relatively stable. We found that a solution based TiOx layer synthesized using a sol-gel chemistry method was very effective in protecting the active layer from degradation

Adsorption and photocatalytic performance of bentonite-titanium dioxide composites for methylene blue and rhodamine B decoloration.

Bentonite − TiO2 composites werepreparedbyimpregnationofTiO2 and bentonite, followed by microwave irradiation processes. The composites were characterized using FTIR, SEM, XRD, and nitrogen sorption methods. Anatase phase of TiO2 in all composites are observed through XRD diffraction peaks and surface morphology of the composites. The adsorption and photocatalytic capabilities of the composites were tested in liquid phase adsorption of methylene blue and Rhodamine B. The adsorption and photocatalytic degradation experiments were conducted in the presence or absence of UV light irradiation. Langmuir and Freundlich models were employed to correlate the experimental adsorption data, and it was found that Langmuir gave better performance in correlating the experimental data. Modification of Langmuir equation to accommodate photocatalytic degradation process was conducted, and the model could represent the experimental results very well

Stability of High Band Gap P3HT : PCBM Organic Solar Cells Using TiOx Interfacial Layer

We fabricated a poly[3-hexylthiophene] (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) organic photovoltaic cells (OPCs) using TiOx interfacial layer. We performed optimization processes for P3HT : PC61BM with the TiOx layer. We found that a solution based TiOx layer coated at a spin speed of 3000 rpm improved the photon absorption of the active layer. An optimized TiOx layer was also used as the interfacial layer to investigate the stability of P3HT : PC61BM OPC. After 70 days of storage, we observed that the short-circuit current density (JSC) dropped by 16.2%, fill factor (FF) dropped by 10.6%, and power conversion efficiency (PCE) dropped approximately by 25%, while the open-circuit voltage (VOC) remained relatively stable. We found that a solution based TiOx layer synthesized using a sol-gel chemistry method was very effective in protecting the active layer from degradation

Controlled synthesis of ZnO spheres using structure directing agents

Controlled liquid phase deposition has been developed for fabricating zinc oxide (ZnO) nano/microspheres using a mixture of precursor solution of zinc acetate dihydrate, ammonium hydroxide, and structure directing agents (SDAs) such as ethanol and urea. We found that ZnO spheres can be formed when the SDAs are optimized with the proper pH values. At pH values less than 12, an anisotropic growth of ZnO flowers and rod structures was produced with/without SDAs. On the contrary, at a pH value of 12 the directional growth of ZnO was absolutely controlled and an isotropic growth of ZnO spheres was developed with the presence of SDAs. We also found that the volume ratio of ethanol and urea in the solution was a key factor to modulate the uniform size distribution and diameter of the ZnO spheres from nanometer to micrometer range. © 2013 Elsevier B.V.1871sciescopu

Metode pembuatan katalis heterogen berbasis tembaga untuk produksi biodiesel

5 Invensi ini berhubungan dengan metode pembuatan katalis heterogen berbasis tembaga untuk membuat biodiesel, lebih khususnya biodiesel yang dihasilkan dari reaksi transesterifikasi antara minyak kelapa sawit dan metanol. Metode 10 pembuatan katalis heterogen berbasis tembaga dalam bentuk metalorganic framework (MOF) dengan bahan dasar logam dari senyawa CuSO4.5H2O dan ligan 1,3,5-benzenetricarboxylic acid (BTC). Padatan MOF yang dihasilkan digunakan sebagai katalis heterogen pembuatan biodiesel dengan karakteristik struktur kristal yang 15 dominan, bentuk batang, luas permukaan BET 1.000-1.100 m2/g dan volume pori total 1,6-1,8 cm3/g, dan stabilitas termal sampai dengan 300C; dan menghasilkan yield biodiesel sampai dengan 91% dari reaksi transesterifikasi minyak kelapa sawit dan metanol (dengan perbandingan 1:4 sampai dengan 1:8) dan kosentrasi 20 katalis 0,04-0,1% pada suhu 60C selama 4 jam; serta dapat digunakan sebagai katalis sampai dengan 5 kali

Highly efficient degradation of organic pollutant mixtures by a Fe(III)-based MOF-catalyzed Fenton-like process in subcritical water

Propylene glycol monomethyl ether acetate (PGMEA) photoresist solvent and monoaromatics are typical organic pollutants found in the wastewater discharged from semiconductor manufacturing processes. Conventional treatment technologies, however, remain mostly ineffective to eliminate these pollutants from aqueous streams. Herein, we developed a novel strategy for highly efficient degradation of PGMEA and archetypal monoaromatics (i.e., benzene, toluene, xylene, phenol, and cresol) in aqueous solution by heterogeneous Fenton-like process with a flexible Fe-MOF (MIL-88B) under mild subcritical water (SCW) condition (100 �C). The as-synthesized MIL-88B(Fe) microbipyramids possess large pore channels (�32 nm) and open iron sites. The results showed that the SCW-mediated heterogeneous Fenton-like process at 100 �C with an optimal catalyst loading of 1 wt% exhibited a remarkable degradation performance toward target organic pollutants in a multicomponent system, affording a 92% total organic carbon (TOC) removal in 60 min. This mineralization efficiency was found to be notably superior to those of traditional homogeneous Fenton (FeSO4/H2O2; �54%) and Fenton-SCW (�60%) processes. The practicability of this approach was demonstrated using real world water samples (i.e., river water, fishpond water, and wastewater) with >80% TOC removal efficiency. This study showed that the heterogeneous Fenton-like process utilizing an inexpensive, nontoxic, and reusable MIL-88B(Fe) MOF under mild SCW conditions is a promising strategy for treating semiconductor waste effluents and environmental water matrices containing toxic recalcitrant organics in an eco-friendly and efficient manner