A fundamental understanding of the relationship between the bulk morphology and device performance is required for the further development of bulk heterojunction organic solar cells. Here, non‐optimized (chloroform cast) and nearly optimized (solvent‐annealed o‐dichlorobenzene cast) P3HT:PCBM blend films treated over a range of annealing temperatures are studied via optical and photovoltaic device measurements. Parameters related to the P3HT aggregate morphology in the blend are obtained through a recently established analytical model developed by F. C. Spano for the absorption of weakly interacting H‐aggregates. Thermally induced changes are related to the glass transition range of the blend. In the chloroform prepared devices, the improvement in device efficiency upon annealing within the glass transition range can be attributed to the growth of P3HT aggregates, an overall increase in the percentage of chain crystallinity, and a concurrent increase in the hole mobilities. Films treated above the glass transition range show an increase in efficiency and fill factor not only associated with the change in chain crystallinity, but also with a decrease in the energetic disorder. On the other hand, the properties of the P3HT phase in the solvent‐annealed o‐dichlorobenzene cast blends are almost indistinguishable from those of the corresponding pristine P3HT layer and are only weakly affected by thermal annealing. Apparently, slow drying of the blend allows the P3HT chains to crystallize into large domains with low degrees of intra‐ and interchain disorder. This morphology appears to be most favorable for the efficient generation and extraction of charges.

Derivatization of fullerene (C 60 ) with "branched" aliphatic chains can soften C 60 -based materials and enables the formation of thermotropic liquid crystals as well as room temperature nonvolatile liquids with tunable viscosity. The chain branching methodology with optoelectronic activity of C 60 is believed to be a powerful technique to develop C 60 -based soft and fl exible photovoltaic devices. As featured in:See H. Li et al., J. Mater. Chem. C, 2013, 1, 1943

The interaction of spherical gold nanoparticles (Au-NPs) with microgels composed of chemically crosslinked poly-(N-isopropylacrylamide) is reported. Simple mixing of the two components leads to adsorption of the gold particles onto the microgels. Different loading densities can be achieved by varying the ratio of gold particles to microgel particles. The adsorption of gold nanoparticles is analysed by TEM, UV-Vis absorption spectroscopy and SAXS. The influence of the microgel mesh size on the adsorption of gold nanoparticles is investigated by using microgels with three different cross-linker densities. The results suggest a strong relationship between the nanoparticle penetration depth and the cross-linker density. This, in turn, directly influences the optical properties of the colloids due to plasmon resonance coupling. In addition, information about the mesh size distribution of the microgels is obtained. For the first time the change in optical properties by varying cross-linker density and temperature is directly related to the formation of dimers of gold particles, proven by SAXS.

Each year we are bombarded with B.Sc. and Ph.D. applications from 8 students that want to improve the world. They have learned that their future depends 9 on changing the type of fuel we use and that solar energy is our future. The hope and 10 energy of these young people will transform future energy technologies, but it will 11 not happen quickly. Organic photovoltaic devices are easy to draw AU1, but the mate-12 rials, processing steps, and ways of measuring the properties of the materials are 13 very complicated. It is not trivial to make a systematic measurement that will 14 change the way other research groups think or practice. In approaching this chapter, 15 we thought about what a new researcher would need to know about organic 16 photovoltaic devices and materials in order to have a good start in the subject. [1][2][3][4]. Similar 43 to the gold rush in the 1800s and the oil boom in the 1900s, intellectual property on 44 new technologies is now the boom industry for innovative people to become rich 45 and influential fast. In the twenty-first century, scientists and engineers are the 46 pioneers and our ideas are the prize. One of the most alluring energy technologies of 47 the past decade has been organic photovoltaics (OPV). This technology is alluring 48 because it could potentially reduce the cost of producing photovoltaic 49 (PV) modules and thereby make solar energy cost-competitive with fossil fuels. 50 As can be seen in Fig. 1, the allure of OPV brought thousands of scientists and 51 engineers into this new field, generating an exponential increase in scientific 52 knowledge (as measured by the number of scientific AU4 articles) in this area. The 53 sharp focus on OPV technology has led to an explosion of interest in enabling 54 technologies such as polymer synthesis, polymer physics, microstructural measure-55 ment techniques, multiscale modeling, photophysics, organic electronics, organic-56 inorganic hybrid materials, etc. All of this intense focus into one research area has 57 also created intense competition between research groups. With so many new 58 scientific articles published yearly, it is impossible to read them all, and repeat or 59 redundant articles have become unfortunately and unavoidably common. Even 60 review articles and books about OPV have proliferated, making production of an 61 original perspective difficult and a complete literature review impractical. We 62 apologize in advance if any important work is not cited here. 63Under this backdrop, we have decided to produce an article that is designed to be 64 helpful to students and postdocs who are entering this field. Rather than focusing on 65 the efficiency of devices or the morphology of materials (subjects that are covered 66 very well elsewhere), we instead focus some attention on how to approach OPV 67 research from a more practical (laboratory-based) perspective. Section 1 introduces A.J. Moulé et al. 68OPV devices, modules, and scale-up. Section 2 discusses fabrication of poly-3- Device Characterist...