Metal-halide perovskite nanocrystals (NCs) are promising photonic materials for use in solar cells, light-emitting diodes, and lasers. The optoelectronic properties of these devices determined by the excitons exciton complexes confined their NCs. In this study, we relaxation dynamics charged biexcitons CsPbBr3 NCs using femtosecond transient-absorption (TA), time-resolved photoluminescence (PL), single-dot second-order photon correlation spectroscopy. Decay times ∼40 ∼200 ps were obtained...

All inorganic CsPbBr3 perovskite quantum dots (QDs) are potential emitters for electroluminescent displays. We have developed a facile hot-injection method to partially replace the toxic Pb2+ with highly stable Sn4+ . Meanwhile, absolute photoluminescence yield of CsPb1-x Snx Br3 increased from 45 % 83 SnIV substitution. The transient absorption (TA) exciton dynamics in undoped and CsPb0.67 Sn0.33 QDs at various excitation fluences were determined by femtosecond absorption, time-resolved...

Combining the superior optical properties of their bulk counterparts with quantum confinement effects, lead halide perovskite nanocrystals are unique laser materials low-threshold gain. In such nonlinear regimes, multiple excitons generated in and strongly affect gain through many-body interactions. Here, we investigate exciton-exciton interactions CsPbI3 by femtosecond transient absorption spectroscopy. From analysis induced signal observed immediately after pump excitation, estimated...

We study the origin of photoluminescence (PL) intermittency in formamidinium lead bromide (FAPbBr3, FA = HC(NH2)2) nanocrystals and impact postsynthetic surface treatments on PL intermittency. Single-dot spectroscopy revealed existence different individual exhibiting either a blinking (binary on–off switching) or flickering (gradual undulation) behavior Although lifetimes clearly correlate with absorption cross sections, those show no correlation sections. This indicates that has an...

Lead halide perovskite nanocrystals (NCs) are one of the most anticipated and promising materials for light-emitting diodes lasers because their high photoluminescence quantum yields (PLQYs). However, formation trions (charged excitons) in NCs reduces PLQYs. Here, we clarify trion mechanism CsPbBr3 by analyzing excitation fluence dependence transient absorption signals. Under weak photoexcitation, formed charge carrier trapping at surface states. In contrast, biexciton Auger recombination...

Lead halide perovskite nanocrystals (NCs) have superior photoluminescence (PL) properties, such as high PL quantum yields and wide wavelength tunability, for optoelectronic applications. Here, we report the spectra of single formamidinium lead FAPbX3 (X = Br, I) NCs examined by single-dot spectroscopy at low temperature. We found four peaks in low-energy region below strong exciton peak that originate from two longitudinal-optical (LO) phonon replicas PL, biexcitons, charged excitons...

Lead halide perovskite nanocrystals (NCs) have outstanding photoluminescence (PL) properties and excellent potential for light-emitting diodes single-photon sources. Here, we report the multiple-peak structures originating from excitons, trions, biexcitons in low-temperature PL spectra of single CsPbBr3 NCs. We found fine-structure splitting peaks bright excitons also longitudinal-optical (LO)-phonon replicas excitons. LO-phonon trions are clearly observed under strong photoexcitation, which...

The generation of high-order harmonics from hybrid organic–inorganic perovskites (HOIPs) is demonstrated by the excitation with a strong mid-infrared laser pulse. We prepare three types HOIP polycrystalline thin film samples solution processes (MAPbX3; MA = CH3NH3+; X I, Br, Cl). sample (MAPbBr3) are more than tenfold stronger those well-studied GaSe crystal despite their comparable bandgap energies, implying that band-to-band transition HOIPs causes higher yields.

Lead halide perovskites are promising semiconductors for high-performance photonic devices. Because the refractive index determines optimal design and performance limit of semiconductor devices, its change upon external modulations most critical properties advanced applications. Here, we report that perovskite CH3NH3PbCl3 shows a distinct decrease with increasing temperature, i.e., large negative thermo-optic coefficient, which is opposite to those conventional inorganic semiconductors. By...

Abstract All inorganic CsPbBr 3 perovskite quantum dots (QDs) are potential emitters for electroluminescent displays. We have developed a facile hot‐injection method to partially replace the toxic Pb 2+ with highly stable Sn 4+ . Meanwhile, absolute photoluminescence yield of CsPb 1− x Br increased from 45 % 83 IV substitution. The transient absorption (TA) exciton dynamics in undoped and 0.67 0.33 QDs at various excitation fluences were determined by femtosecond absorption, time‐resolved...

Metal halide perovskites have emerged as versatile photonic device materials because of their outstanding band structure and excellent optical properties. Here, we determined the excitation wavelength dependences two-photon absorption coefficient Kerr-effect-induced nonlinear refractive index $\mathrm{C}{\mathrm{H}}_{3}\mathrm{N}{\mathrm{H}}_{3}\mathrm{PbC}{\mathrm{l}}_{3}$ perovskite single crystals by means Z-scan method. From theoretical analysis, found that electron-hole interaction,...

Surface defects and synthesis methods play important roles in the photoluminescence quantum yield (PLQY), stability, device performance of lead halide perovskite dots (PQDs). In this study, we report a quadruple-ligand (tri-n-octylphosphine, didodecyldimethylammonium bromide, tetraoctylammonium oleic acid) assisted room-temperature method for synthesizing CsPbBr3 QDs (RT-CsPbBr3) with an absolute PLQY 83%. X-ray photoelectron spectroscopy confirms high completeness Pb-Br octahedron through...

Lead halide perovskite (APbX3) nanocrystals exhibit photoluminescence (PL) with both wide wavelength tunability and high quantum efficiency. While the Pb-X6 octahedra mainly determines near-band-edge optical properties A-site cation affects structural stability, role of in determining is still unclear. Here, we report PL three types lead bromide APbBr3 different cations [A = HC(NH2)2+, CH3NH3+, Cs+], as revealed by single-dot spectroscopy, discuss influence on spectrum. The nanocrystal size...

Lead halide perovskite nanocrystals are promising light emitting materials with high photoluminescence quantum yields and widely tunable emission wavelengths. Their optical responses significantly influenced by efficient nonradiative Auger recombination of trions (charged excitons) biexcitons. Here, we report the observation positive negative in formamidinium lead bromide discuss their role dynamics. It is found that addition copper thiocyanate causes an additional intermediate state...

Charge carrier dynamics in perovskite CH3NH3PbI3 solar cells were studied by means of microscopic photoluminescence (PL) and photocurrent (PC) imaging spectroscopy. The PL intensity, lifetime, PC intensity varied spatially on the order several tens micrometers. Simultaneous image measurements revealed a positive correlation between negative intensities. These correlations due to competition photocarrier injection from layer into charge transport recombination within layer. Furthermore, we...

Abstract Single crystals of methylammonium lead trihalide perovskites with high optical transparency and well‐defined facets are grown via solution process. Using these high‐quality crystals, the photocarrier‐induced refractive‐index change is observed for first time in organic–inorganic hybrid perovskites. The photorefractive properties measured using a laser interferometric technique that enables to monitor time‐resolved refractive phase shifts. It found shifts determined by initial...

The superior electrical conductivity and optical transparency of indium tin oxide (ITO) make it an ideal electrode material for use in optoelectronic devices such as solar cells. When ITO electrodes are fabricated on very thin plastic substrates, however, the internal stress layer causes substrate to deform, severely limiting device's performance. Herein, is shown that bilayers composed amorphous base a crystalline overlayer lead deformation‐free electrodes. It optimized bilayer structure...

We demonstrate evidence of localized states near the band edge lead halide perovskite semiconductor CH3NH3PbI3 thin films. In these films, high-temperature tetragonal and low-temperature orthorhombic phases coexist at low temperatures. determine exact energy level in phase via photocurrent (PC) beat spectroscopy. The lack observation photoluminescence absorption measurements indicates that density is fairly even solution-processed polycrystalline Ultrafast PC spectroscopy enables us to...

We study the sub-band-gap high harmonic generation (HHG) in a methylammonium lead trichloride single crystal. Anisotropy crystal orientation dependence of yield is observed, and varies substantially with electric field strength midinfrared laser pulse used for excitation. Our real-time ab initio simulations reproduce experimental results well also show that HHG independent interband decoherence time. Based on microscopic analysis intraband current, we reveal this perovskite semiconductor...

The cylindrical Hall thruster (CHT) is an attractive approach to achieve a long lifetime operation especially in low power space applications. Because of the larger volume-to-surface ratio than conventional coaxial thrusters, thrusters are characterized by reduced heating parts and potential lower erosion. Existing CHTs can feature short channel order sustain high ionization discharge. A 5.6 cm diameter was developed operated with without region channel, range 70–300 W. It shown that CHT...

Lead halide perovskite nanocrystals (NCs) are a class of promising light-emitting materials and have been considered as gain media in lasers. Strong exciton-exciton interactions NCs cause an energy shift the lowest optical transition affect threshold. Here, we clarify dynamics highly photoexcited CsPbI3 by double-pump transient absorption spectroscopy. This method provides control over population each excited state varying time interval between two pump pulses. We find that band-edge induced...

High harmonic generation (HHG) in solids shows interesting behavior owing to their crystal structures. Here, the authors investigate a prominent example: HHG GaAs can be enhanced by elliptically polarized light excitation. Remarkably, enhancement is accompanied emergent nonlinear optical activity, and it become salient only at particular ``intermediate'' excitation strengths. These results indicate that key for lies interference among emission processes, revealing not material properties but...