A general and efficient biomimetic method for the synthesis of aldimines from aldehydes and compounds bearing the NH2 group in the presence of pyrrolidine as a catalyst has been developed. These organocatalytic reactions, based on the application of the concept of nucleophilic catalysis, proceed with outstanding yields in the absence of acids and metals under simple conditions and minimum experimental manipulation. The method has been mainly applied to the synthesis of N-sulfinyl and N-sulfonyl imines, but its general validity has been proven with the preparation of representative N-phosphinoyl, N-alkyl, and N-aryl imines. These unprecedented reactions, which presumably occur via iminium activation without requiring acidic conditions, are an interesting and competitive alternative to the classical methods for preparing aldimines.

The formation of nitrones by direct condensation between equimolecular amounts of N-substituted hydroxylamine hydrochlorides and aromatic or aliphatic aldehydes is efficiently promoted by pyrrolidine in a matter of minutes under very mild conditions in almost quantitative yields after a simple filtration through a short pad of silica gel. According to theoretical, spectroscopic, and experimental studies, this success is due to the ability of pyrrolidine to liberate the hydrochloride of the hydroxylamine and catalyze the reaction via iminium activation ion. Moreover, a cooperative pyrrolidine/pyrrolidinium chloride effect facilitates several steps of the catalytic cycle through proton transfer without hampering the nucleophilicity of the hydroxylamine by protonation.

Organic solar cells (OSCs) that contain small molecules only were prepared with FG1 as the donor, a narrow band gap non-fullerene acceptor MPU4, and a wide band gap PC 71 BM. The OSCs based on optimized FG1:MPU4 (1:1.2) and FG1:PC 71 BM (1:1.5) active layers, respectively, gave power conversion efficiencies (PCEs) of 11.18% with a short circuit current (J SC ) of 19.54 mA/cm 2 , open circuit voltage (V OC ) of 0.97 V, and fill factor (FF) of 0.59, and 6.62% with a J SC of 12.50 mA/ cm 2 , V OC of 0.84 V, and FF of 0.63%, respectively. A PCE of 13.26% was obtained from the optimized ternary FG1:PC 71 BM:MPU4 (1:0.3:0.9) OSCs and this arises because of the boost in a J SC of 21.91 mA/cm 2 and FF of 0.68. The V OC of the ternary OSCs (0.89 V) lies between those for the OSCs based on FG1:MPU4 and FG1:PC 71 BM, which indicates the formation of an alloy of the two acceptors. The increase in J SC and FF in the ternary OSCs may result from the efficient energy transfer from PC 71 BM to MPU4 as well as more charge-transfer donor/acceptor interfaces, enhanced charge carrier mobilities resulting in better adjusted charge transport, and lower bimolecular and trap-assisted recombination. The appropriate phase separation, increased crystallinity, and reduced π−π stacking distance in the ternary active layer are consistent with the enhancement in the FF for OSCs based on a ternary active layer. The results of this work suggest the merging of the fullerene acceptor into the non-fullerene acceptor to form a fullerene/non-fullerene acceptor alloy, and this may be a viable approach to obtain high-performance OSCs.

The influence of CPDTV-oligomer length and terminal acceptor units in the efficiency of OSCs with PC71BM is studied.

An efficient organic solar cell (OSC) based on a ternary active layer consisting of two conjugated small‐molecule (SM) donors (FG3 and FG4) and a well‐known nonfullerene SM acceptor (Y6) is fabricated using a nonhalogenated solvent. An overall power conversion efficiency (PCE) of 14.31% is achieved, higher than that for the binary counterparts, i.e., 10.75% and 11.07% for FG3:Y6 and FG4:Y6, respectively. The short‐circuit current density (JSC) of the ternary active layer organ is related to the broader absorption spectra when compared with the binary active layers. The open‐circuit voltage (VOC) of the ternary active layer‐based OSCs falls between those of the OSCs based on FG3:Y6 and FG4:Y6, a situation that is consistent with the lowest unoccupied molecular orbital (LUMO) level of both SM donors (FG3 and FG4), and forms the alloy between the two donors. The overlap of the absorption spectra of FG4 with the photoluminescence of FG3 confirms the energy transfer from FG3 to FG4 and this leads to improvement in JSC. The balanced charge transport, reduced charge recombination, and the fast charge extraction in the ternary active layer leads to the higher fill factor (FF) value. A combination of all of these effects affords a high PCE value.