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A new class of biomimetic J-aggregates based on an amphiphilic BF₂-azadipyrromethene dye is reported by Z. Chen, F. Würthner, et al. in their Communication (DOI: 10.1002/anie.201701788). The J-aggregate (aggregate II) is formed via kinetically favored metastable aggregate I intermediate and characterized by a sharp and intense J-band at 799 nm. The optical properties and the rod-like morphology of aggregate II resemble those for the natural bacteriochlorophyll J-aggregates found in chlorosomes of green bacteria.

The light intensity dependence of the main photoelectrical parameters of the nonfullerene small-molecule bulk heterojunction (BHJ) solar cells p-DTS(FBTTh₂)₂:perylene diimide (T1:PDI) shows that the nongeminate recombination losses play an important role in this system. A simple approach for the quantitative analysis of capacitance spectroscopy data of the organic BHJ solar cells, which allows to determine the density of free charge carriers as a function of applied bias under standard working conditions, is demonstrated. Using the proposed capacitance spectroscopic technique, the nongeminate recombination losses in the T1:PDI solar cells are quantitatively characterized in the scope of the bimolecular- and trap-assisted recombination mechanisms. Their contributions are separately analyzed within a wide range of the applied bias.

A simple method for the determination of the density of free charge carriers and quantification of nongeminate recombination losses in organic-bulk heterojunction solar cells, based on the analysis of capacitance spectroscopy data, is presented. The proposed method is applied to the analysis of nongeminate recombination losses in nonfullerene T1: perylene diimide small-molecule solar cells in the scope of bimolecular- and trap-assisted recombination mechanisms under 1 sun illumination.