Ландшафтное проектирование (городские объекты) : учеб.-метод. пособие

Spray coating, a cost-effective and scalable technique, has been employed for fabricating titania films for solid-state dye-sensitized solar cells (ssDSSCs). The spray deposition of films is inherently based on kinetic processes with great complexity, which poses great challenges in its understanding. In the present work, the kinetics of the structure evolution of deposited films are investigated by in situ grazing-incidence small-angle x-ray scattering during spray deposition. The spray-solution is prepared via a polystyrene-block-polyethylene oxide (PS-b-PEO) template assisted sol-gel synthesis. It is turned into nanostructured titania/PS-b-PEO composite films via spray deposition. The information about nanostructure length scales of the composite film is obtained in real-time and in situ, revealing the morphological evolution during the spray deposition. The resulting mesoporous titania films serve as photoanodes of ssDSSCs, which couple with the solution-cast hole transport layer to form the active layers. The well working ssDSSCs demonstrate the successful use of spray deposition as a large-scale manufacturing process for photoanodes

Light‐Induced and Oxygen‐Mediated Degradation Processes in Photoactive Layers Based on PTB7‐Th

Low-bandgap polymers are sensitive to various degradation processes, which strongly decrease their lifetime. The chemical and physical changes occurring in the low-bandgap polymer with benzodithiophene units poly[4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and its blend with the fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) are followed during irradiation-induced aging by combination of various characterization methods. The active layer morphology is investigated using atomic force microscopy (AFM) as well as in-operando grazing incidence small angle X-ray scattering (GISAXS), indicating morphological alterations and material loss due to chemical modifications. Optical spectroscopy gives insights into these chemical processes which lead to significant absorption losses under ambient conditions. Independent of the energy of the absorbed photons, but only in combination with oxygen, the excitation of the polymer leads to a fatal increase in oxidation probability. Fourier transform infrared (FTIR) data highlight the sensitivity of the conjugated polymer backbone to oxidation, a result of lost conjugation and therefore absorption capability. With combined AFM height and infrared (IR) mapping, the chemical degradation and material loss is confirmed on a nanoscale. Although the chemical structure is seriously damaged, the blend morphology is not undergoing major changes

Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films.

In order to tailor the assembling of polymers and organic molecules, a deeper understanding of the kinetics involved in thin film production is necessary. While post-production characterization only provides insight on the final film structure, more sophisticated experimental setups are needed to probe the structure formation processes in situ during deposition. The drying kinetics of a deposited organic thin film strongly influences the assembling process on the nanometer scale. This work presents an experimental setup that enables fine control of the atmosphere composition surrounding the sample during slot die coating, while simultaneously probing the film formation kinetics using in situ grazing incidence X-ray scattering and spectroscopy

Development of the Morphology during Functional Stack Build-up of P3HT:PCBM Bulk Heterojunction Solar Cells with Inverted Geometry

Highly efficient poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells are achieved by using an inverted geometry. The development of the morphology is investigated as a function of the multilayer stack assembling during the inverted solar cell preparation. Atomic force microscopy is used to reveal the surface morphology of each stack, and the inner structure is probed with grazing incidence small-angle X-ray scattering. It is found that the smallest domain size of P3HT is introduced by replicating the fluorine-doped tin oxide structure underneath. The structure sizes of the P3HT:PCBM active layer are further optimized after thermal annealing. Compared to devices with standard geometry, the P3HT:PCBM layer in the inverted solar cells shows smaller domain sizes, which are much closer to the exciton diffusion length in the polymer. The decrease in domain sizes is identified as the main reason for the improvement of the device performance

Arrangement of Maghemite Nanoparticles via Wet Chemical Self-Assembly in PS- b -PNIPAM Diblock Copolymer Films

The structure and magnetic behavior of hybrid films composed of maghemite (-Fe2O3) nanoparticles (NPs) and an asymmetric diblock copolymer (DBC) polystyrene61-block-polyN-isopropylacrylamide115 are investigated. The NPs are coated with PS chains, which allow for a selective incorporation inside the PS domains at different NP concentrations. Upon incorporation of low amounts of NPs into the DBC thin films, the initial parallel (to film surface) cylinder morphology changes to a well ordered, perpendicularly oriented one. The characteristic domain distance of the DBC is increased due to the swelling of the PS domains with NPs. At higher NP concentrations, the excess NPs which can no longer be embedded in the PS domains, are accumulated at the film surface, and NP aggregates form. Irrespective of NP concentration, a superparamagnetic behavior of the metal oxide-DBC hybrid films is found. Such superparamagnetic properties make the established hybrid films interesting for high density magnetic storage media and thermoresponsive magnetic sensors.This work was supported by the BMBF (German Ministry of Research and Education) Grant No. 03DU03MU and by the Nanosystems Initiative Munich (NIM). Y.Y. and B.S. acknowledge the China Scholarship Council (CSC). V.K. thanks the Bavarian State Ministry of Education, Science and the Arts for funding this research work via project “Energy Valley Bavaria”.Peer reviewe

Spray deposition of titania Films with Incorporated Crystalline Nanoparticles for All-solid-state Dye-Sensitized Solar Cells Using P3HT

Spray coating, a simple and low‐cost technique for large‐scale film deposition, is employed to fabricate mesoporous titania films, which are electron‐transporting layers in all‐solid‐state dye‐sensitized solar cells (DSSCs). To optimize solar cell performance, presynthesized crystalline titania nanoparticles are introduced into the mesoporous titania films. The composite film morphology is examined with scanning electron microscopy, grazing incidence small‐angle X‐ray scattering, and nitrogen adsorption–desorption isotherms. The crystal phase and crystallite sizes are verified by X‐ray diffraction measurements. The photovoltaic performance of all‐solid‐state DSSCs is investigated. The findings reveal that an optimal active layer of the all‐solid‐state DSSC is obtained by including 50 wt% titania nanoparticles, showing a foam‐like morphology with an average pore size of 20 nm, featuring an anatase phase, and presenting a surface area of 225.2 m2 g−1. The optimized morphology obtained by adding 50 wt% presynthesized crystalline titania nanoparticles yields, correspondingly, the best solar cell efficiency of 2.7 ± 0.1%.Financial support by TUM.solar in the context of the Bavarian Collaborative Research Project “Solar Technologies Go Hybrid” (SolTech), by the GreenTech Initiative (Interface Science for Photovoltaics – ISPV) of the EuroTech Universities and by the Nanosystems Initiative Munich (NIM) is gratefully acknowledged. V.K. thanks the Bavarian State Ministry of Sciences, Research and Arts for funding this research work via project “Energy Valley Bavaria.” L.S., W.W., and Y.Y. acknowledge the China Scholarship Council (CSC)