This article describes the performance of organic photovoltaic (OPV) devices, incorporating three different polymer/fullerene derivative blends, under low‐level lighting conditions. The devices exhibit much higher power conversion efficiencies (PCEs) under indoor lighting conditions than they do under sunlight. The best‐performing device is capable of delivering a power output of 22.57 μW cm−2, corresponding to a PCE of 13.76%, under illumination with indoor lighting conditions at 500 lux. Increasing the open‐circuit voltage (Voc) of the OPV devices is the most critical factor for achieving high device performance for low‐power indoor applications. Therefore, the device power output will be maximized if we could obtain a larger energy difference between the highest occupied molecular orbital of the polymer donor and the lowest unoccupied molecular orbital of the electron acceptor, thereby ensuring a high value of Voc.

A new acceptor unit anthra[1,2-b: 4,3-b': 6,7-c'']trithiophene-8,12-dione (А3Т) (A2) is synthesized and used to design D-A 1 -D-A 2 medium bandgap donor copolymers with same thiophene (D) and A2 units but different A1, i.e., fluorinated benzothiadiazole (F-BTz) and benzothiadiazole (BTz) denoted as P130 and P131, respectively. Their detailed optical and electrochemical properties are examined. The copolymers show good solubility in common organic solvents, broad absorption in the visible spectral region from 300 to 700 nm, and deeper HOMO levels of −5.45 and −5.34 eV for P130 and P131, respectively. Finally, an optimized polymer solar cell (PSC) based on P131 as the donor and narrow bandgap non-fullerene small molecule acceptor Y6 demonstrated a power conversion efficiency (PCE) of >11.13%. To further improve the efficiency of the non-fullerene PSC, the P130 is optimized by introducing a fluorine atom into the BTz unit, F-BTz acceptor unit, and PCE PSC based on P130: Y6 active layer increased to >15.28%, which is higher than that for the non-fluorinated analog P131:Y6. The increase in the PCE for former PSC is attributed to the more crystalline nature and compact 𝝅-𝝅 stacking distance, leading to more balanced charge transport and reduced charge recombination. These remarkable results demonstrate that A3T-based copolymer P130 with F-BTz as the second acceptor is a promising donor material for high-performance PSCs.

This paper describes the preparation of fluorinated graphene nanosheets (FGNs) through photoexfoliation of fluorinated graphite (FG) in the liquid phase. We discovered that UV irradiation of FG dispersions in N-methyl-2-pyrolidone facilitated exfoliation to give FGNs. Transmission electron microscopy and atomic force microscopy revealed that the average thickness of the FGNs was approximately 3 nm; they were considerably thinner than the nanosheets prepared using a conventional sonication approach. Furthermore, when the FGNs were deposited uniformly onto substrates (through spin coating), they formed effective cathode interlayers for polymer solar cells (PSCs), the efficiency of which was 60% greater than that of PSCs containing FGNs prepared through ultrasonication.

New Activated Bisfluoroaromatic Compounds.-Palladium catalyzed cross-coupling of the bis(phenyl bromides) (I) with acetylene (II) gives the bis (fluorophenylethynyl) derivatives ( III) which are smoothly oxidized to the corresponding bis( fluorophenylglyoxalyl) derivatives (IV). Compounds (IV) can be used in the synthesis of polyethers showing liquid crystalline properties. -(RUSANOV, A. L.; KESHTOV, M. L.; BELOMOINA, N. M.; MIKITAEV, A. K.; SARKISYAN, G. B.; KESHTOVA, S. V.; Izv.

Organic photovoltaic (OPV) devices still work efficiently after sunset! To save energy and improve the sustainability of the many electronic systems, such as Internet of Thing (IoT), distributed harvesters of energy from the local environment could be particularly critical. Photovoltaic devices could be an energy source for such needs. Although traditional solar cells exhibit very high power conversion efficiencies (PCEs) under illumination at about 100 mW cm−2 of solar irradiation, the efficiency drops significantly with the decreasing light intensity. Herein (article No. http://doi.wiley.com/10.1002/solr.201700174), OPV devices may provide a solution; their PCEs are much higher under indoor lighting conditions than they are under sunlight. For example, the device is capable of delivering a power output of 22.57 μW cm−2, corresponding to a PCE of 13.76%, under illumination with indoor lighting conditions at 500 lux. These results might open up new directions for further improving the device performance of OPV devices for local energy harvesters under low‐power lighting applications.