Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investi...Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investigate the lattice dynamics of Cs_(2)AgInCl_(6)using first-principles calculations.By explicitly incorporating four-phonon scattering and wave-like phonon tunneling,we predict a k_(l)of 0.52 W·m^(-1)·K^(-1)with a remarkably weak temperature dependence(k_(l)∝T^(-0.31)),confirming the intrinsically glass-like ultralow k_(l)in Cs_(2)AgInCl_(6).Further analyses reveal that hierarchical chemical bonds,loosely bonded rattling atoms and a mixed crystalline-liquid state collectively induce strong anharmonicity manifested in flat phonon modes.These factors dominate the glass-like thermal transport component of k_(l).This work uncovers the underlying mechanisms governing the unusual thermal transport properties in lead-free HDPs and offers guiding principles for designing novel energy conversion technologies.展开更多
Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention.In this work,a Cr^(3+)-doped halide perovskite,Cs_(2)AgInCl_(6):Cr^(3+),which exhibits broadband ne...Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention.In this work,a Cr^(3+)-doped halide perovskite,Cs_(2)AgInCl_(6):Cr^(3+),which exhibits broadband near-infrared(NIR)emission is first obtained via the traditional high temperature solid-state reaction.A broad emission band ranging from 850 to 1350 nm centered at 1010 nm with a full-width at halfmaximum(FWHM)of 180 nm is assigned to the spin-allowed ^(4)T_(2)→^(4)A_(2) transition of octahedrally coordinated Cr^(3+)ions in a very weak crystal-field environment.The excitation bands centered at 353,565 and 800 nm can be attributed to the absorption of the Cs_(2)AgInCl_(6) host,the Cr^(3+)d-d transitions of ^(4)A_(2)→^(4)T_(1) and ^(4)A_(2)→^(4)T_(2),respectively.Upon 760 nm excitation,the photoluminescence quantum yield(PLQY)of Cs_(2)AgIn_(0.9)Cl_(6):0.1Cr^(3+)is about∼22.03%.Cs_(2)AgInCl_(6):Cr^(3+)phosphors with such broadband NIR emission have potential in phosphor converted light emitting diodes(pc-LEDs)which have applications in bioimaging and biomonitoring.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12204482),the Natural Science Foundation of Shanxi Province(Grant No.202403021221164)Higher education teaching reform and innovation project of Shanxi Province(Grant No.J20220480)the Natural Science Foundation of Hainan Province(Grant Nos.525MS080 and 225MS076).
文摘Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investigate the lattice dynamics of Cs_(2)AgInCl_(6)using first-principles calculations.By explicitly incorporating four-phonon scattering and wave-like phonon tunneling,we predict a k_(l)of 0.52 W·m^(-1)·K^(-1)with a remarkably weak temperature dependence(k_(l)∝T^(-0.31)),confirming the intrinsically glass-like ultralow k_(l)in Cs_(2)AgInCl_(6).Further analyses reveal that hierarchical chemical bonds,loosely bonded rattling atoms and a mixed crystalline-liquid state collectively induce strong anharmonicity manifested in flat phonon modes.These factors dominate the glass-like thermal transport component of k_(l).This work uncovers the underlying mechanisms governing the unusual thermal transport properties in lead-free HDPs and offers guiding principles for designing novel energy conversion technologies.
基金supported by the National Natural Science Foundation of China(No 51972020,51832005 and 51702329)Fundamental Research Funds for the Central Universities(FRF-TP-18-005A1)Beijing Natural Science Foundation(No 2182080).
文摘Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention.In this work,a Cr^(3+)-doped halide perovskite,Cs_(2)AgInCl_(6):Cr^(3+),which exhibits broadband near-infrared(NIR)emission is first obtained via the traditional high temperature solid-state reaction.A broad emission band ranging from 850 to 1350 nm centered at 1010 nm with a full-width at halfmaximum(FWHM)of 180 nm is assigned to the spin-allowed ^(4)T_(2)→^(4)A_(2) transition of octahedrally coordinated Cr^(3+)ions in a very weak crystal-field environment.The excitation bands centered at 353,565 and 800 nm can be attributed to the absorption of the Cs_(2)AgInCl_(6) host,the Cr^(3+)d-d transitions of ^(4)A_(2)→^(4)T_(1) and ^(4)A_(2)→^(4)T_(2),respectively.Upon 760 nm excitation,the photoluminescence quantum yield(PLQY)of Cs_(2)AgIn_(0.9)Cl_(6):0.1Cr^(3+)is about∼22.03%.Cs_(2)AgInCl_(6):Cr^(3+)phosphors with such broadband NIR emission have potential in phosphor converted light emitting diodes(pc-LEDs)which have applications in bioimaging and biomonitoring.
