Hot carrier cooling in lead halide perovskites probed by two-pulse photovoltage correlation spectroscopy

The next-generation hot-carrier solar cells,which can overcome the Shockley-Queisser limit by harvesting excessenergy from hot carriers,are receiving increasing attention.Lead halide perovskite(LHP)materials are considered aspromising candidates due to their exceptional photovoltaic properties,good stability and low cost.The cooling rate of hotcarriers is a key parameter influencing the performance of hot-carrier solar cells.In this work,we successfully detected hotcarrier dynamics in operando LHP devices using the two-pulse photovoltage correlation technique.To enhance the signalto-noise ratio,we applied the delay-time modulation method instead of the traditional power modulation.This advancementallowed us to detect the intraband hot carrier cooling time for the organic LHP CH_(3)NH_(3)PbBr_(3),which is as short as 0.21 ps.In comparison,the inorganic Cs-based LHP CsPbBr_(3)exhibited a longer cooling time of around 0.59 ps due to differentphonon contributions.These results provide us new insights into the optimal design of hot-carrier solar cells and highlightthe potential of LHP materials in advancing solar cell technology.

Spectroscopy and carrier dynamics of one-dimensional nanostructures

In recent years,one-dimensional(1D)nanomaterials have raised researcher's interest because of their unique structur-al characteristic to generate and confine the optical signal and their promising prospects in photonic applications.In this re-view,we summarized the recent research advances on the spectroscopy and carrier dynamics of 1D nanostructures.First,the condensation and propagation of exciton-polaritons in nanowires(NWs)are introduced.Second,we discussed the properties of 1D photonic crystal(PC)and applications in photonic-plasmonic structures.Third,the observation of topological edge states in 1D topological structures is introduced.Finally,the perspective on the potential opportunities and remaining chal-lenges of 1D nanomaterials is proposed.

Perovskite quantum dot lasers

Owing to the excellent properties of perovskite quantum dots(QDs),such as an easy synthesis process,high photoluminescence quantum yields,high defect tolerance,and tunable bandgap with different elements,laser actions have been widely conducted.Over the past few years,several approaches have been used for successfully creating perovskite QD lasers.In this review,we summarize the progress of perovskite QD lasers from the aspects of laser theory,characteristics and applications of QD lasers,advantages of perovskite materials for lasers,factors influencing the QD laser threshold,two-photon pumped QD lasers,and perovskite QD laser stability.At the same time,aiming at existing problems,possible solutions and prospects are presented.

Growth of metal halide perovskite materials

Perovskite materials,especially metal halide perovskites,exhibit excellent properties,such as large optical coefficients,high carrier mobilities,long carrier lifetimes,tunable resistivities,large X-ray attenuation coefficients,and simple processing techniques.In recent decades,perovskites have attracted significant attention in the photoelectric field due to their versatile utility in solar cells,light-emitting diodes,photodetectors,X/γ-ray detectors,and lasing.However,the wide applicability of perovskites highly depends on the quality of perovskite crystals and films.Thus far,several perovskite growth technologies and methods have emerged.Therefore,this review classified and summarized the main methods that have been employed to achieve perovskite growth in recent years,including the solution temperaturelowering(STL)method,inverse temperature crystallization(ITC),anti-solvent vapor-assisted crystallization(AVC),spin coating,and chemical vapor deposition(CVD).Through analysis and summary,it has been determined that the STL,ITC,and AVC methods are mainly used to grow high-quality perovskite single crystals.While the spin-coating method has a significant advantage in the preparation of perovskite films,the CVD method is propitious in the fabrication of a variety of morphologies of micro/nano perovskite materials.We hope that this review can be a comprehensive reference for scientific researchers to prepare perovskite-related materials.

Cavity engineering of two-dimensional perovskites and inherent light-matter interaction

Two-dimensional(2D)perovskites are hybrid layered materials in which the inorganic lattice of an octahedron is sandwiched by organic layers.They behave as a quantum-well structure exhibiting large exciton binding energy and high emission efficiency,which is excellent for photonic applications.Hence,the cavity modulation and cavity devices of 2D perovskites are widely investigated.In this review,we summarize the rich photophysics,synthetic methods of different cavity structures,and the cavity-based applications of 2D perovskites.We highlight the strong exciton–photon coupling and photonic lasing obtained in different cavity structures.In addition,functional optoelectronic devices using cavity structures of 2D perovskites are also reviewed.

Lead-free perovskites: growth, properties, and applications

Lead halide perovskites have attracted extensive attention in recent years because of their excellent photoelectronic properties, such as high absorption coefficients,carrier mobilities, defect tolerances, and photoluminescence efficiencies. However, a key issue hindering their commercial application is the toxicity of lead. Replacing lead with other nontoxic elements is a promising solution to this problem.Considering their atomic radii, relative atomic masses, and electron arrangements, perovskites based on Sn, Bi, Sb, and other elements instead of Pb have been widely synthesized.Here, we summarized the growth methods, photoelectric properties, and device applications of these lead-free perovskites. First, we introduced several common growth methods for lead-free perovskites, including solution methods,solid-state reaction, and chemical vapor deposition methods.Second, we discussed the photoelectric properties and methods for optimizing these properties of lead-free perovskites with different structure dimensions. Finally, the applications of lead-free perovskites in solar cells, light-emitting diodes,and X-ray detectors were examined. This review also provides suggestions for future research on lead-free perovskites.