LeasyScan: a novel concept combining 3D imaging and lysimetry for high-throughput phenotyping of traits controlling plant water budget

In this paper, we describe the thought process and initial data behind the development of an imaging platform (LeasyScan) combined with lysimetric capacity, to assess canopy traits affecting water use (leaf area, leaf area index, transpiration). LeasyScan is based on a novel 3D scanning technique to capture leaf area development continuously, a scanner-to-plant concept to increase imaging throughput and analytical scales to combine gravimetric transpiration measurements. The paper presents how the technology functions, how data are visualised via a web-based interface and how data extraction and analysis is interfaced through ‘R’ libraries. Close agreement between scanned and observed leaf area data of individual plants in different crops was found (R2 between 0.86 and 0.94). Similar agreement was found when comparing scanned and observed area of plants cultivated at densities reflecting field conditions (R2 between 0.80 and 0.96). An example in monitoring plant transpiration by the analytical scales is presented. The last section illustrates some of the early ongoing applications of the platform to target key phenotypes: (i) the comparison of the leaf area development pattern of fine mapping recombinants of pearl millet; (ii) the leaf area development pattern of pearl millet breeding material targeted to different agro-ecological zones; (iii) the assessment of the transpiration response to high VPD in sorghum and pearl millet. This new platform has the potential to phenotype for traits controlling plant water use at a high rate and precision, of critical importance for drought adaptation, and creates an opportunity to harness their genetics for the breeding of improved varieties

P3HT-Based Solar Cells: Structural Properties and Photovoltaic Performance

Each year we are bombarded with B.Sc. and Ph.D. applications from students that want to improve the world. They have learned that their future depends on changing the type of fuel we use and that solar energy is our future. The hope and energy of these young people will transform future energy technologies, but it will not happen quickly. Organic photovoltaic devices are easy to sketch, but the materials, processing steps, and ways of measuring the properties of the materials are very complicated. It is not trivial to make a systematic measurement that will change the way other research groups think or practice. In approaching this chapter, we thought about what a new researcher would need to know about organic photovoltaic devices and materials in order to have a good start in the subject. Then, we simplified that to focus on what a new researcher would need to know about poly-3-hexylthiophene:phenyl-C61-butyric acid methyl ester blends (P3HT: PCBM) to make research progress with these materials. This chapter is by no means authoritative or a compendium of all things on P3HT:PCBM. We have selected to explain how the sample fabrication techniques lead to control of morphology and structural features and how these morphological features have specific optical and electronic consequences for organic photovoltaic device applications

Structural and optical properties of both pure poly (3-octylthiophene) (P3OT) and P3OT/fullerene films

We have investigated the structural and optical properties of P3OT and P3OT/fullerene thin films in view of their application as active layer in plastic solar cells. Films of these materials were prepared by spin coating from toluene solutions onto silicon substrates. Their optical properties were studied by spectroscopic ellipsometry, which provides the anisotropic dielectric function of the films. Moreover, structural properties were studied using X-ray diffraction. A close correlation between the results obtained by both methods could be found. Especially, the strong optical anisotropy of the films can be explained in terms of a preferable orientation of the polymer chains parallel to the substrate. The effect of the optical anisotropy on the performance of optoelectronic devices is discussed. (C) 2003 Elsevier B.V. All rights reserved

Correlation between structural and optical properties of composite polymer/fullerene films for organic solar cells

We investigate thin poly(3-hexylthiophene-2,5-diyl)/[6,6]-phenyI C-61 butyric acid methyl ester (P3HT/PCBM) films, which are widely used as active layers in plastic solar cells. Their structural properties are studied by grazing-incidence X-ray diffraction (XRD). The size and the orientation of crystalline]P3HT nanodomains within the films are determined. PCBM crystallites are not detected in thin films by XRD. Upon annealing, the P3HT crystallinity increases, leading to an increase in the optical absorption and spectral photocurrent in the low-photon-energy region. As a consequence, the efficiency of P3HT/PCBM solar cells is significantly increased. A direct relation between efficiency and P3HT crystallinity is demonstrated

Conjugated Polymers: Relationship Between Morphology and Optical Properties

In this Chapter we will start by briefly summarising the basic concepts of the electronic structure of conjugated polymers. This will enable the discussion of the relevant descriptions of the dielectric function. We will relate these descriptions to the model parameterisations which are used in advanced ellipsometric analysis of thin films such as those used in devices for organic photovoltaics (OPVs) and light emitting diodes (OLEDs). Amongst other things, such parametric descriptions are useful to deal with structural changes in conjugated polymer thin films. Once the models are presented, we will provide representative examples of the nexus between morphology and optical constants, and how the latter can be employed to infer aspects of the former. First, we will discuss how chain conformation affects the optical properties. Then, we will explain the anisotropic behaviour of conjugated polymer films due to their intrinsic molecular anisotropy and review different cases (f. i., oriented films or semicrystalline polymers). We will also describe structural changes that occur upon blending polymers with fullerenes and concomitant variations of the optical properties. Here we will focus on state of the art low band gap polymers mixed with fullerenes. Finally, real-time ellipsometric experiments in which these structure-property relationships can be exploited will be presented.The authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through grant MAT2015-70850-P and the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496).Peer reviewe