Synthesis And Optical Properties Of Organic Lead Halide Perovskites

Organic lead halide perovskites have attracted great attention due to their excellent performance in solar cells field.The power conversion efficiency of hybrid lead halide perovskites solar cells has reached about 20%in a short time,which is approaching the performance of state-of-the art commercial monocrystalline silicon solar cells.There are a lot of approaches to prepare perovskites,for example,vapor-phase deposition,solution-chemistry approaches,hot injection method,room temperature recrystallization and so on.Various structures of perovskites?nanoplatelets,nanorods and quantum dots?can be synthesized via controlling the condition of the experiment.The CH₃NH₃PbX3?X = Cl,Br,I?exhibit excellent optical properties.The band gap and emission wavelength of perovskites can be easily tuned in a broad spectra region through changing the chemical composition,morphology and size.The luminescent quantum yield of perovskites could achieve up to 90%.Besides,the long carrier lifetime and diffusion length demonstrate these perovskites are promising optical gain materials.Beyond the application in solar cells,the lead halide perovskites have also showed the great potentials in the application of light-emitting diodes,lasers and photodetectors.In this paper,we focus our attention on the preparation of organic lead halide perovskites and their optical properties.First of all,we prepared the CH₃NH₃PbBr3 perovskite nanocrystals,nanoplatelets,rods and films.The morphology and optical properties of these perovskites were studied.We deeply investigated the multiphoton emission from perovskite films.Furthermore,we tried employing anodic aluminum oxide templates to prepare perovskite rods,which would provide a new idea in this field.In the second part,we paid most attention to the quantum confinement effect in perovskite nanoplatelets.The thickness of perovskite nanoplatelets could be manipulated by changing the ratio of reactants.A large blue-shift could be observed in absorption and photoluminescence spectra when three dimensional perovskites turning into two dimensional layered perovskites.As the thickness of perovskite nanoplatelets decreased,the electron-hole Coulomb interaction would become more strong,which would lead to a large exciton binding energy and excitonic effect could be observed at room temperature.We measured the exciton binding energy of monolayer perovskite nanoplatelets,its value?218 meV?is far larger than that in three dimensional perovskite counterparts.Last but not least,we were trying preparing the metal-perovskites hybrid nanostructures,which would provide a reference in designing new structures in this field.