Organic solar cells demonstrate external quantum efficiencies and fill factors approaching those of conventional photovoltaic technologies. However, as compared to the optical gap of the absorber materials, their open-circuit voltage is much lower, largely due to the presence of significant nonradiative recombination. In this work, we study a large data set of published and new material combinations and find that non-radiative voltage losses decrease with increasing charge-transfer state energies. This observation is explained by considering non-radiative charge-transfer state decay as electron transfer in the Marcus inverted regime, being facilitated by a common skeletal molecular vibrational mode. Our results suggest an intrinsic link between non-radiative voltage losses and electron-vibration coupling, indicating that these losses are unavoidable. Accordingly, the theoretical upper limit for the power conversion efficiency of single junction organic solar cells would be reduced to about 25.5% and the optimal optical gap increases to (1.45-1.65) eV, i.e. (0.2-0.3) eV higher than for technologies with minimized non-radiative voltage losses. Manuscript: "Intrinsic Non-Radiative Voltage Losses in Fullerene-Based OSCs" J. Benduhn et al.

The copper-catalyzed cycloaddition reaction between a propargyl-appended europium complex and azidomethylferrocene yields a d-f dyad whose photophysical properties can be reversibly switched by varying the oxidation state of the ferrocene chromophore.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract: A study of the anion-binding properties of three structurally related lanthanide complexes which all contain chemically identical anion-binding motifs has revealed dramatic differences in their anion affinity.

The equilibria for core Ca2+ replacement by Ln3+ in copper(II) 15-MC-5 complexes have been investigated using a series of visible spectrophotometric titrations of calcium(II) metallacrowns ({CaII[15-MCCuII(N)(L)-5]}2+) with Ln3+ ions (H2L = pheha, (S)-α-phenylalaninehydroxamic acid, or trpha, (S)-α-tryptophanhydroxamic acid). These studies allowed the determination of the equilibrium constants for the reaction {CaII[15-MCCuII(N)(L)-5]}2+ + Ln3+ → {LnIII[15-MCCuII(N)(L)-5]}3+ + Ca2+ in methanol/water 9:1 (Ln3+ = La3+, Gd3+, Dy3+, Er3+) or 99:1 (Ln3+ = La3+, Nd3+, Gd3+, Dy3+, Er3+, Yb3+), respectively. The log K for these reactions decreases with increasing atomic number of the lanthanide(III), ranging from 6.1 to 3.91 in methanol/water 9:1. The same behavior is observed in methanol/water 99:1, although the constants are uniformly lower (log K = 4.09−2.52). A significant thermodynamic selectivity was observed for the later lanthanides (Gd3+−Yb3+) while a smaller selectivity is present throughout the beginning of the series (La3+−Gd3+). This observation has been interpreted on the basis of the size correspondence between the metal ions and the metallacrown cavity. The overall stability of the {CaII[15-MCCuII(N)(L)-5]}2+ in methanol/water 9:1 has been determined by pH-spectrophotometric titrations with HCl. The resulting log K values are 63.46(12) and 65.05(13) for pheha and trpha, respectively (Ca2+ + 5Cu2+ + 5HL− = {CaII[15-MCCuII(N)(L)-5]}2+ +5H+). The stability of both the La3+ and Ca2+ 15-metallacrown-5 complexes in the presence of high Na+ concentrations has also been demonstrated by spectophotometric studies. Based upon these observations, the preference of the 15-MC-5 for Ca2+ complexation compared to crown ethers has been quantitatively demonstrated for the first time.