Near-infrared (NIR) light detection is key to an ever-growing demand for technical solutions in applications such as surveillance systems, facial recognition, industrial sorting and inspection, pulse oximetry, optical coherence tomography, and

Organic photovoltaics (OPV) represent a thin‐film PV technology that offers attractive prospects for low‐cost and aesthetically appealing (colored, flexible, uniform, semitransparent) solar cells that are printable on large surfaces. In bulk heterojunction (BHJ) OPV devices, organic electron donor and acceptor molecules are intimately mixed within the photoactive layer. Since 2005, the power conversion efficiency of said devices has increased substantially due to insights in the underlying physical processes, device optimization, and chemical engineering of a vast number of novel light‐harvesting organic materials, either small molecules or conjugated polymers. As Nature itself has developed porphyrin chromophores for solar light to energy conversion, it seems reasonable to pursue artificial systems based on the same types of molecules. Porphyrins and their analogues have already been successfully implemented in certain device types, notably in dye‐sensitized solar cells, but they have remained largely unexplored in BHJ organic solar cells. Very recent successes do show, however, the strong (latent) prospects of porphyrinoid semiconductors as light‐harvesting and charge transporting materials in such devices. Here, an overview on the state‐of‐the‐art of porphyrin‐based solution‐processed BHJ OPV is provided and insights are given into the pathways to follow and hurdles to overcome toward further improvements of porphyrinic materials and devices.

Although a strong link between the molar mass of conjugated polymers and the performance of the resulting polymer:fullerene bulk heterojunction organic solar cells has been established on numerous occasions, a clear understanding of the origin of this connection is still lacking. Moreover, the usual description of molar mass and polydispersity does not include the shape of the polymer distribution, although this can have a significant effect on the device properties. In this work, the effect of molar mass distribution on photovoltaic performance is investigated using a combination of structural and electro-optical techniques for the state-of-the-art low bandgap copolymer PTB7. Some of the studied commercial PTB7 batches exhibit a bimodal distribution, of which the low molar mass fraction contains multiple homocoupled oligomer species, as identified by MALDI-TOF analysis. This combination of low molar mass and homocoupling drastically reduces device performance, from 7.0 to 2.7%. High molar mass batches show improved charge carrier transport and extraction with much lower apparent recombination orders, as well as a more homogeneous surface morphology. These results emphasize the important effect of molar mass distributions and homocoupling defects on the operation of conjugated polymers in photovoltaic devices.

This manuscript reports a universal chain-growth polymerization protocol for conjugated polymers. Herein, the Pd-based catalyst moiety dissociates from the growing active center into the solution and therefore, the controlled chaingrowth character is not relying on any specific, system-related complexation, as is the case in polymerization methods reported before. This makes the protocol applicable on a broad range of monomers and, furthermore, also allows an easy onepot synthesis of block-copolymers by successive monomer addition. A chain-growth polymerization mechanism for poly(3-hexylthiophene) (P3HT) and poly(9,9-dioctylfluorene) (PF) and all-conjugated block-copolymers of them is presented. Moreover, the sequence of monomer addition in the synthesis of these conjugated block-copolymers is unimportant, which is unique. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 5339-5349, 2011