Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles c...Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles core(dibenzofuran,dibenzothiophene,dibenzothiophene sulfone)were designed and synthesized,and their applications in PSCs were investigated.The intrinsic properties(CV,UV-vis,hole mobility and conductivity)were systematically investigated,demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs.Benefiting from the excellent hole mobility and conductivity,good film forming ability,and outstanding charge extraction and transport capability of S-CBz,FAPbI_(3)-based PSCs using S-CBz as HTM achieved a PCE of 25.0%,which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions(23.9%).Furthermore,due to the interaction between S and Pb^(2+),SCBz-based PSC devices exhibited improved stability.This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.展开更多
1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orb...1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.展开更多
Excited-state intramolecular proton transfer(EsiPT)involves photochemical tautomerization between two excited states(E*and K*)via intramolecular proton transfer.Developing polymer photochromism based on the photochemi...Excited-state intramolecular proton transfer(EsiPT)involves photochemical tautomerization between two excited states(E*and K*)via intramolecular proton transfer.Developing polymer photochromism based on the photochemical tautomerization of organic ESiPT molecules has been rarely reported.We report the ESIPT molecule HBT-2oH exhibits concentration-dependent photochromic behavior in a polyurethane(PU)network.At low concentrations,HBT-2oH primarily exists in the trans-enol configuration without intramolecular OH..N hydrogen bonds in PU,emitting blue fluorescence at~464 nm(enol emission).Upon UV irradiation,the dihedral angle between the proton donor and acceptor twists to form an intramolecular OH-.N H-bond,converting trans-enol to cis-enol and resulting in ESIPT with pale yellow fluorescence at~603 nm(keto emission).The photochromic effect of HBT-2OH@PU diminishes at high concentrations due to that aggregation favors the cis-enol form.Control molecules HBT,HBO-2OH,and HBl-2OH show no photochromism in PU,confirming that ethanolyl branches and intramolecular OH...S hydrogen bonds stabilize the trans-enol configuration of HBT-2OH.Incorporating these molecules into PMMA and PCL networks demonstrates that increased free volume and smaller aggregates enhance photochromism by reducing resistance to dihedral angle twisting.Density functional theory(DFT)calculations further confirm stable intramolecular heteroatomic hydrogen bonds(OH..S)exist in HBT-2OH.This study offers new theoretical insights and opens avenues for research on polymer based photochromic materials.展开更多
To commercialize fuel cells and metal-air batteries, cost-effective, highly active catalysts for the oxygen reduction reaction （ORR） must be developed. Herein, we describe the development of low-cost, heteroatom （N...To commercialize fuel cells and metal-air batteries, cost-effective, highly active catalysts for the oxygen reduction reaction （ORR） must be developed. Herein, we describe the development of low-cost, heteroatom （N, P, Fe） ternary-doped, porous carbons （HDPC）. These materials are prepared by one-step pyrolysis of natural tea leaves treated with an iron salt, without any chemical and physical activation. The natural structure of the tea leaves provide a 3D hierarchical porous structure after carbonization. Moreover, heteroatom containing organic compounds in tea leaves act as precursors to functionalize the resultant carbon frameworks. In addition, we found that the polyphenols present in tea leaves act as ligands, reacting with Fe ions to form coordination compounds; these complexes acted as the precursors for Fe and N active sites. After pyrolysis, the as-prepared HDPC electrocatalysts, especially HDPC-800 （pyrolyzed at 800℃）, had more positive onsets, half-wave potentials, and higher catalytic activities for the ORR, which proceeds via a direct four-electron reaction pathway in alkaline media, similar to commercial Pt/C catalysts. Furthermore, HDPC-X also showed enhanced durability and better tolerance to methanol crossover and CO poisoning effects in comparison to commercial Pt/C, making them promising alternatives for state-of-the-art ORR electrocatalysts for electrochemical energy conversion. The method used here provides valuable guidelines for the design of high-performance ORR electrocatalysts from natural sources at the industrial scale.展开更多
基金supported by the financial support from the National Natural Science Foundation of China(Nos.22279046,22179053)Natural Science Excellent Youth Foundation of Jiangsu Province(No.BK20220112)Special Foundation for Carbon Peak Carbon Neutralization Technology Innovation Program of Jiangsu Province(No.BE2022026-2).
文摘Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles core(dibenzofuran,dibenzothiophene,dibenzothiophene sulfone)were designed and synthesized,and their applications in PSCs were investigated.The intrinsic properties(CV,UV-vis,hole mobility and conductivity)were systematically investigated,demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs.Benefiting from the excellent hole mobility and conductivity,good film forming ability,and outstanding charge extraction and transport capability of S-CBz,FAPbI_(3)-based PSCs using S-CBz as HTM achieved a PCE of 25.0%,which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions(23.9%).Furthermore,due to the interaction between S and Pb^(2+),SCBz-based PSC devices exhibited improved stability.This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.
基金This project was supported by the National Natural Science Foundation of China.
文摘1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.
基金supported by the National Natural Science Foundation of China(22375013,22175015,21704002)the Beijing Natural Science Foundation(2182054)+1 种基金the Big Science Project from BUCT(XK180301)the Fundamental Research Funds forthe Central Universities to Z.Y.Ma.
文摘Excited-state intramolecular proton transfer(EsiPT)involves photochemical tautomerization between two excited states(E*and K*)via intramolecular proton transfer.Developing polymer photochromism based on the photochemical tautomerization of organic ESiPT molecules has been rarely reported.We report the ESIPT molecule HBT-2oH exhibits concentration-dependent photochromic behavior in a polyurethane(PU)network.At low concentrations,HBT-2oH primarily exists in the trans-enol configuration without intramolecular OH..N hydrogen bonds in PU,emitting blue fluorescence at~464 nm(enol emission).Upon UV irradiation,the dihedral angle between the proton donor and acceptor twists to form an intramolecular OH-.N H-bond,converting trans-enol to cis-enol and resulting in ESIPT with pale yellow fluorescence at~603 nm(keto emission).The photochromic effect of HBT-2OH@PU diminishes at high concentrations due to that aggregation favors the cis-enol form.Control molecules HBT,HBO-2OH,and HBl-2OH show no photochromism in PU,confirming that ethanolyl branches and intramolecular OH...S hydrogen bonds stabilize the trans-enol configuration of HBT-2OH.Incorporating these molecules into PMMA and PCL networks demonstrates that increased free volume and smaller aggregates enhance photochromism by reducing resistance to dihedral angle twisting.Density functional theory(DFT)calculations further confirm stable intramolecular heteroatomic hydrogen bonds(OH..S)exist in HBT-2OH.This study offers new theoretical insights and opens avenues for research on polymer based photochromic materials.
基金Acknowledgements The authors thank the financial support by the National Natural Science Foundation of China （No. 51273008 and 51473008）, the National High-Tech Research and Development Program （No. 2012AA030305）, the National Basic Research Program （No. 2012CB933200）, and NSF （No. CMMI-1400274 and AIR-IIP-1343270）.
文摘To commercialize fuel cells and metal-air batteries, cost-effective, highly active catalysts for the oxygen reduction reaction （ORR） must be developed. Herein, we describe the development of low-cost, heteroatom （N, P, Fe） ternary-doped, porous carbons （HDPC）. These materials are prepared by one-step pyrolysis of natural tea leaves treated with an iron salt, without any chemical and physical activation. The natural structure of the tea leaves provide a 3D hierarchical porous structure after carbonization. Moreover, heteroatom containing organic compounds in tea leaves act as precursors to functionalize the resultant carbon frameworks. In addition, we found that the polyphenols present in tea leaves act as ligands, reacting with Fe ions to form coordination compounds; these complexes acted as the precursors for Fe and N active sites. After pyrolysis, the as-prepared HDPC electrocatalysts, especially HDPC-800 （pyrolyzed at 800℃）, had more positive onsets, half-wave potentials, and higher catalytic activities for the ORR, which proceeds via a direct four-electron reaction pathway in alkaline media, similar to commercial Pt/C catalysts. Furthermore, HDPC-X also showed enhanced durability and better tolerance to methanol crossover and CO poisoning effects in comparison to commercial Pt/C, making them promising alternatives for state-of-the-art ORR electrocatalysts for electrochemical energy conversion. The method used here provides valuable guidelines for the design of high-performance ORR electrocatalysts from natural sources at the industrial scale.
