An ESIPT based fluorescent probe, containing a hydroxyphenyl-benzothiazole fluorophore and an oxime reaction site, serves as a selective probe for a nerve gas mimic, diethyl cyanophosphonate (DECP), in solutions and the gas phase. The probe exhibits more than a 60-fold fluorescence enhancement in the presence of the target, has a limit of detection of 1.3 nM and displays high selectivity toward DECP over closely related substances, including sulfur mustard stimulants and other nerve agent mimics. Moreover, composite nanofibers with relatively low concentrations of the probe (0.45% w/w) exhibit distinct color and fluorescence changes upon exposure to DECP vapor.

Binary organic photovoltaics (OPVs) fabricated by single-step (SS) deposition of a binary blend of polymer (or small molecule) donor and fullerene acceptor (SS binary OPV) are widely utilized. To improve the OPV performance, SS ternary OPVs utilizing a ternary blend consisting of two (or one) electron donor(s) and one (or two) electron acceptor(s) have been studied. SS ternary OPVs require more sensitive and complex optimization processes to optimize bulk heterojunctions with bicontinuous nanoscale phase separation of the donor and acceptor. We demonstrated a novel ternary OPV fabricated by sequential (SQ) deposition of a single polymer donor and a binary mixture consisting of a phenyl-C-butyric acid methyl ester (PCBM) and nonfullerene acceptor, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3- d:2,3'- d']- s-indaceno[1,2- b:5,6- b']dithiophene (ITIC). In the SQ ternary OPV, PCBM effectively created a bicontinuous pathway for charge transport with a polymer, and ITIC mainly enhanced light absorption and photovoltage. This complementary effect was not observed in an SS ternary OPV utilizing the same donor and acceptors. Due to these complementary effects, the SQ ternary OPV exhibited a power conversion efficiency of 6.22%, which was 52 and 37% higher than that of the SQ binary OPV and the SS ternary OPV, respectively. In addition, the thermal stability of the SQ ternary OPV was found to be superior to that of the SS ternary OPV.

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efficiency (PCE) of OPVs has already reached 14.2%. [1] However, a major drawback for the commercialization of OPVs is their long-term stability under continuous operation. Especially, OPVs suffer from a rapid decrease in PCE during initial device operation, which is known as the "burn-in loss." [2][3][4][5][6] The origin of the burn-in loss is thought to be mainly related to the instability of the bulk heterojunction (BHJ) morphology and/or interface rather than the photo-oxidation of the photoactive layer.Morphological instability of photoactive layer is one of critical issues of burn-in loss in OPV. [7][8][9][10][11] Because electron-donating and electron-accepting materials are blended in a photoactive layer to form metastable BHJ, applying high-temperature heat or strong light can cause microscopic morphology changes resulting in the burn-in loss. [8,9] For typical OPVs utilizing a BHJ, a photoactive layer (blend of electrondonating conjugated polymer and electron-accepting fullerene) is sandwiched between two electrodes (anode/cathode) with their corresponding charge-transporting (hole/electron) interlayers. [12] The interlayers minimize the energy barrier between the photoactive layer and electrodes, and thereby enhance the collection efficiencies of electrons/holes on the cathode/ anode. Thus, significant efforts have been made to develop various electron-transporting layer (ETL) materials for OPVs such as transition metal oxides, [13] carbon-based materials, [14] polymers, [15] low work function metal salts, [16] and organicinorganic hybrids. [17] Among various ETL materials, transition metal oxides are commonly utilized because of their adequate highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, stability, transparency, and excellent electron mobility. [5,18] Additionally, transition metal oxide ETLs provide an excellent barrier property against oxygen and metal electrode diffusion compared to organic ETL materials. Various types of transition metal oxides such as zinc oxide (ZnO), [19] titanium oxide (TiO 2 or TiO x ), [20][21][22] tin oxide (SnO 2 or SnO x ), [23] and niobium oxide (Nb 2 O 5 or NbO x ) [24] have been explored for use as ETL materials for OPVs. Generally, the transition metal oxide layer is deposited by vacuum deposition techniques such as sputtering, [22] atomic layer deposition, [25] or It is revealed that instability of interface between photoactive layer and electron-transporting layer (ETL) is one of the causes of the rapid degradation of organic photovoltaics (OPV) performance during initial operation (burn-in loss) under the light soaking. The stability of OPV is greatly enhanced by applying a robust ETL composed of TiO 2 nanoparticles (TNPs). The TNPs bound with π-π interactive 3-phenylpentane-2,4-dione (TNP-Ph) form more robust ETLs than those bound with van der Waals interactive 3-methyl-2,4pentanedione TNP (TNP-Me). The OPV with TNP-Ph maintains 73% of its initial power conversion efficiency (PCE) after 1000 h of light soa...