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Nehir Biyoteknoloji Ltd. www.nehirbt.com This protocol describes the extreme high height microfluidic channel fabrication. In this case the height of the channels is 500 µm and this required some modifications on the previous protocol.

Nehir Biyoteknoloji Ltd. www.nehirbt.com This protocol explains the usage of PDMS microfluidics with an application example of analysis by microscope. Interpretive pictures are added.

Nehir Biyoteknoloji Ltd. www.nehirbt.com

Nehir Biyoteknoloji Ltd. www.nehirbt.com

Nehir Biyoteknoloji Ltd. www.nehirbt.com

Nehir Biyoteknoloji Ltd. www.nehirbt.com

The application of new polymer materials for organic solar cells requires a detailed understanding of the orientation and the electronic properties of the system because these have a dramatic effect on the device performance and efficiency. The films were prepared by doctor blade casting, a simple preparation route from solution. We study the orientation of the low band gap polymers poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) and poly-[2,6-(4,4-bis(2-ethyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-5,8-(2,3-dioctylquinoxaline)] (PCPDTQ) as well as of the state of the art polymer poly(3-hexyl-thiophene) (P3HT) using near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Clear angular dependence in the NEXAFS spectra is observed for P3HT and PCPDTBT pointing to well-orientated films.

The authors investigated organic tandem solar cells with solution processed recombination contacts made from a TiO2 sol in combination with PEDOT:PSS. Tandem cells were prepared either with two P3HT:PCBM-based subcells or by combining PCDTBT:PC[70]BM and PCPDTBT:PC[70]BM. Optical modeling is used to predict experimental short circuit currents of the tandem solar cells as a function of layer thickness. Both types of tandem cells yield energy conversion efficiencies of ca. 3.3%. We propose that a significant improvement of the performance of the PCDTBT:PC[70]BM - PCPDTBT:PC[70]BM tandem is possible by optimization of the recombination contact and layer thicknesses of both subcells.

We demonstrate the importance of the nanocrystal surface treatment and the inorganic composition for hybrid solar cells. Mixtures of CdSe nanorods and CdSe quantum dots integrated in hybrid solar cells together with the conjugated polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) perform better than nanorod and quantum dot only based devices. In addition larger sized quantum dots show a similar improvement after integration in respective solar cells. Power conversion efficiency values exceeding 3% are observed. A first result on the shelf lifetime of such a device is highlighted.

We report on the efficiency enhancement for bulk-heterojunction hybrid solar cells based on hexanoic acid treated trioctylphosphine/oleic acid-capped CdSe quantum dots (QDs) and low bandgap polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4 H -cyclopenta[2,1- b ;3,4- b ′]-dithiophene)- alt -4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) compared to devices based on poly(3-hexylthiophene) (P3HT). Photovoltaic devices with optimized polymer:QD weight ratio, photoactive film thickness, thermal annealing treatment, and cathode materials exhibited a power conversion efficiency of 2.7% after spectral mismatch correction, which is the highest reported value for spherical CdSe QD based photovoltaic devices. The efficiency enhancement is attributed to the surface treatment of the QDs together with the use of the low bandgap polymer PCPDTBT leading to an increased short-circuit current density due to additional light absorption between 650 and 850 nm. Our results suggest that the hexanoic acid treatment is generally applicable to various ligand-capped CdSe and confirm that low bandgap polymers with adequate HOMO and LUMO levels are promising to be incorporated into hybrid solar cells for further device performance improvement.

Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donor-acceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (eta=8%). pi-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.

We compare standard and inverted bulk heterojunction solar cells composed of PCPDTBT:PC 70 BM blends. Inverted devices comprising 100 nm thick active layers exhibited short circuit currents of 15 mA/cm 2 , 10% larger than in corresponding standard devices. Modeling of the optical field distribution in the different device stacks proved that this enhancement originates from an increased absorption of incident light in the active layer. Internal quantum efficiencies (IQEs) were obtained from the direct comparison of experimentally derived and modeled currents for different layer thicknesses, yielding IQEs of ∼70% for a layer thickness of 100 nm. Simulations predict a significant increase of the light harvesting efficiency upon increasing the layer thickness to 270 nm. However, a continuous deterioration of the photovoltaic properties with layer thickness was measured for both device architectures, attributed to incomplete charge extraction. On the other hand, our optical modeling suggests that inverted devices based on PCPDTBT should be able to deliver high power conversion efficiencies (PCEs) of more than 7% provided that recombination losses can be reduced.

We investigate the effect of molecular doping on the recombination of electrons and holes localized at conjugated-polymer–fullerene interfaces. We demonstrate that a low concentration of p-type dopant molecules (

We have synthesised and characterised a new low-gap conjugated polymer, with a broad absorption profile. In blends with a C(70) derivative we demonstrate power conversion efficiencies of 0.76%. We show electroluminescence from the polymer peaking at 956 nm, and quantum efficiency of 0.02% in a blend.