Highly efficient through-space charge transfer TADF molecule employed in TADF-and TADF-sensitized organic light-emitting diodes

The inception and harnessing of excitons are paramount for the electroluminescence performance of organic light-emitting devices(OLEDs).Through-space charge transfer(TSCT)via intramolecular interaction has proved to be one of the most potent techniques employed to achieve 100% internal quantum efficiency.However,molecular strategies utilized to comprehensively enhance the electroluminescent performance of TSCT emitters regarding improving the photoluminescence quantum yield(PLQY)and elevating the light out-coupling efficiency remain arduous.To surmount this challenge,we deliberately designed and synthesized a proof-of-concept TSCT emitter called CzO-TRZ by incorporating an extra carbazole donor into spiroheterocyclic architecture.The introduction of rigid spiral fragments can immensely boost the horizontal orientation dipole ratio and establish an extra through-bond charge transfer(TBCT)radiative decay channel.As a result,a very high PLQY of 98.7%,fast kRISCof 2.2×10^(5)s^(-1)and high k_(r)^(s) of 2.2×10^(7)s^(-1),and an ultrahigh horizontal dipolar ratio of 90%were concurrently achieved for Cz O-TRZ blended films.Furthermore,corresponding thermally activated delayed fluorescence(TADF)-and TADF-sensitized fluorescence(TSF)-OLEDs based on CzO-TRZ demonstrated external quantum efficiencies(EQEs)of 33.4% and 30.3%,respectively,highlighting its versatile applications as both an emitter and sensitized host.

Gnedenko-Raikov’s Theorem Fails for Exchangeable Sequences

We study the connection between the central limit theorem and law of large numbers for exchangeable sequences, and provide a counterexample to the Gnedenko-Raikov theorem for such sequences.

Fast and highly reversible Na^(+)intercalation/extraction in Zn/Mg dual-doped P2-Na_(0.67)MnO_(2)cathode material for high-performance Na-ion batteries

P2-type layered Na_(0.67)MnO_(2)has been considered to be a promising candidate cathode material for sodium ion batteries.Nevertheless,the undesired phase transitions during operation and the large Na^(+)radius induced sluggish ion diffusion remain the stumbling blocks to realize its high performance.Herein,we propose a Zn/Mg co-doping strategy,which is proved to have bifunctional effects.First,relative to the pristine P2-Na_(0.67)MnO_(2)and the single-ion(Zn/Mg)doped samples,the Zn/Mg dual-doped P2-Na_(0.67)MnO_(2)demonstrates a lower Mn^(3+)/Mn^(4+)ratio and a higher lattice O content,which facilitate the structural stability of the cathode material.More intriguingly,the Zn/Mg co-doping gives rise to enlarged interplanar spacing,which provides spacious ion diffusion channels for fast Na^(+)intercalation/extraction.As a result,the Zn/Mg dual-doped sample exhibits a high Na^(+)diffusion coefficient and a solid-solution reaction during charge/discharge,with a cell volume change determined to be only 0.55%.Taking advantages of the above favorable features,the Zn/Mg dual-doped P2-Na_(0.67)MnO_(2)demonstrates a high rate performance with 67.2 mAh·g^(-1)delivered at 10 C and a decent cycling stability with a capacity retention of 93.8%achieved at 1 C after 100 cycles.This work introduces the Zn/Mg co-doping strategy to simultaneously improve the cycling stability and rate capability of P2-Na_(0.67)MnO_(2),which may offer a promising avenue for further performance enhancement of the layered Na-ion batteries cathode materials.

Conditional Quantile Estimation with Truncated,Censored and Dependent Data

This paper deals with the conditional quantile estimation based on left-truncated and right-censored data.Assuming that the observations with multivariate covariates form a stationary α-mixing sequence,the authors derive the strong convergence with rate,strong representation as well as asymptotic normality of the conditional quantile estimator.Also,a Berry-Esseen-type bound for the estimator is established.In addition,the finite sample behavior of the estimator is investigated via simulations.