A mechanistic framework for hot carrier cooling process in CsPbBr3 PNC is depicted via transient absorption spectroscopy.

Much effort has been dedicated to increase the operational lifetime of blue phosphorescent materials in organic light-emitting diodes (OLEDs), but the reported device lifetimes are still too short for the industrial applications. An attractive method for increasing the lifetime of a given emitter without making any chemical change is exploiting the kinetic isotope effect, where key C-H bonds are deuterated. A computer model identi ed that the most vulnerable molecular site in an Ir-phenylimidazole dopant is the benzylic C-H bond and predicted that deuteration may lower the deactivation pathway involving C-H/D cleavage notably. Experiments showed that the device lifetime (T 70 ) of a prototype phosphorescent OLED device could be doubled to 355 hours with a maximum external quantum e ciency of 25.1% at 1000 cd/m 2 . This is one of the best operational performances of blue phosphorescent OLEDs observed to date in a single stacked cell.

We report the synthesis, structure, and photophysical and electroluminescent (EL) properties of a series of heteroleptic bis(pyridylphenyl)iridium(III) complexes with various ancillary guanidinate ligands. The reaction of the bis(pyridylphenyl)iridium(III) chloride [(ppy)(2)Ir(μ-Cl)](2) with the lithium salt of various guanidine ligands Li{(N(i)Pr)(2)C(NR(1)R(2))} at 80 °C gave in 60-80% yield the corresponding heteroleptic bis(pyridylphenyl)/guanidinate iridium(III) complexes having a general formula of [(ppy)(2)Ir{(N(i)Pr)(2)C(NR(1)R(2))}], where NR(1)R(2) = NPh(2) (1), N(C(6)H(4)(t)Bu-4)(2) (2), carbazolyl (3), 3,6-bis(tert-butyl)carbazolyl (4), N(C(6)H(4))(2)S (5), N(C(6)H(4))(2)O (6), indolyl (7), NEt(2) (8), N(i)Pr(2) (9), N(i)Bu(2) (10), and N(SiMe(3))(2) (11). These heteroleptic cyclometalated (C^N) iridium(III) complexes showed intense absorption bands in the UV region assignable to π-π* transitions and weaker metal-to-ligand charge-transfer transitions extending to the visible region. These complexes also showed intense emissions at room temperature. Their photoluminescence spectra were influenced to some extent by the ancillary guanidinate ligands, giving λ(max) values in the range of 528-560 nm with quantum yields (Φ) of 0.16-0.37 and lifetimes of 0.61-1.43 μs. Organic light-emitting diodes were fabricated by the use of these complexes as dopants in various concentrations (5-100%) in a N,N'-dicarbazolylbiphenyl host. High current efficiency (η(c); up to 137.4 cd/A) and power efficiency (η(p); up to 45.7 lm/W) were observed under appropriate conditions. Their high EL efficiency may result from efficient trapping and radiative relaxation of the excitons formed in the EL process. Because of the steric hindrance of the guanidinate ligands, no significant intermolecular interaction was observed in these complexes, thus leading to the reduction of self-quenching and triplet-triplet annihilation at high currents. The EL emission color could be changed in the range of green to yellow by choosing appropriate guanidinate ligands.

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A significant substituent effect on the EL properties was observed and a heteroleptic iridium(iii) complex with a t-Bu substituted amidinate ligand [(ppy)2Ir{(t-BuN)2CPh}] showed high current and power efficiency.

Nanomaterials-based sensors are in demand for early-stage disease detection as a diagnostic tool. Here, we prepare a non-enzymatic electrochemical sensor using hydrothermally synthesized nano-berries shaped cobalt oxide (Co3O4) nanostructures on...

We report the synthesis, structure, and electrophosphorescence properties of a series of heteroleptic iridium(III) complexes with various cyclometalated (C^N) ligands based on the sterically demanding guanidinate ancillary ligand. The iridium(III) complexes contain two cyclometalated (C^N) ligands and one monoanionic guanidinate ancillary ligand [(N i Pr) 2 C(NPh 2 )]. The reaction of the bis(C^N) iridium(III) chloride [(C^N) 2 Ir(m-Cl)] 2 with the lithium salt of guanidine ligand [Li{(N i Pr) 2 C(NPh 2 )}] at 80 C gave a 65-85% yield of the corresponding heteroleptic [(C^N) 2 Ir{(N i Pr) 2 C(NPh 2 )}] complexes with several different cyclometalated (C^N) ligands such as 2-phenylpyridine (ppy) (1), 2-(2,4-diflurophenyl)pyridine (dfppy) (2), 2-(p-tolyl) pyridine (tpy) (3), benzoquinoline (bzq) (4), 2-phenylbenzoxazole (box) (5), 2phenylbenzothiazole (btz) (6), 2-(2 0 -benzothienyl)pyridine (btp) (7) and 1-phenylisoquinoline (piq) (8).These heteroleptic cyclometalated (C^N) iridium(III) complexes showed intense absorption bands in the UV region, assignable to ligand-centered (p-p*) transitions and lower energy absorption bands that extended to the visible region are mainly derived from spin-forbidden ligand-centered (p-p*) transitions, as well as metal-to-ligand charge transfer (MLCT) transitions. These complexes also showed intense emissions at room temperature, leading to l max values from green (l ¼ 505 nm) to a perfect red colour (l ¼ 655 nm) with quantum yields (F) of 0.18 to 0.64 and phosphorescence lifetimes of 0.78 to 5.80 ms. Organic light-emitting diodes (OLEDs) were fabricated by the use of these complexes as phosphorescent dopants in various concentrations (5-100%) in a N,N 0 -dicarbazolylbiphenyl (CBP) host.High current efficiency (h c ; up to 125 cd A À1 ) and power efficiency (h p ; up to 43.6 lm W À1 ) were observed at appropriate conditions. Because of the steric hindrance of guanidinate ancillary ligands, no significant intermolecular interactions were observed in these complexes, thus leading to the reduction of self-quenching and triplet-triplet (T-T) annihilation at high luminance/currents in OLEDs.

Mining of nutrients from soil is a major problem in developing countries causing soil degradation and threaten long-term food production. The present study attempts to apply NUTrient MONitoring (NUTMON) model for carrying out nutrient budgeting to assess the stocks and flows of nitrogen (N), phosphorus (P), and potassium (K) in defined geographical unit based on the inputs, viz., mineral fertilizers, manures, atmospheric deposition, and sedimentation, and outputs, viz., harvested crop produces, residues, leaching, denitrification, and erosion losses. The study area covers Coimbatore and Erode Districts, which are potential agricultural areas in western agro-ecological zone of Tamil Nadu, India. The calculated nutrient balances for both the districts at district scale, using NUTMON methodology, were negative for nitrogen (N -3.3 and -10.1 kg ha(-1)) and potassium (K -58.6 and -9.8 kg ha(-1)) and positive for phosphorus (P +14.5 and 20.5 kg ha(-1)). Soil nutrient pool has to adjust the negative balance of N and K; there will be an expected mining of nutrient from the soil reserve. A strategy was attempted for deriving the fertilizer recommendation using Decision Support System for Integrated Fertilizer Recommendation (DSSIFER) to offset the mining in selected farms. The results showed that when DSSIFER recommended fertilizers are applied to crops, the nutrient balance was positive. NUTMON-Toolbox with DSSIFER would serve the purpose on enhancing soil fertility, productivity, and sustainability. The management options to mitigate nutrient mining with an integrated system approach are also discussed.