Directing nucleation and growth kinetics in solution-processed hybrid perovskite thin-films

A heightened understanding of nucleation and growth mechanisms is paramount if effective solution processing of organic-inorganic perovskite thin-films for optoelectronic applications is to be achieved. Many fabri- cation techniques have been utilized previously to develop high-performance perovskite layers but there remains an absence of a unifying model that describes accurately the formation of these materials from solution. The present study provides a thorough analysis of nucleation and growth kinetics underpinning the development of hybrid organic-in- organic perovskite thin-films. Through precise control of the perovskite growth conditions the spacing of heteroge- neous nucleation sites was varied successfully from several hundred nanometers to several hundred microns. The crystalline regions surrounding these nuclei were found to comprise clusters of highly-oriented crystal domains exceed- ing 100 pm in diameter. However, no beneficial correlation was found between the size of these well-oriented grain-clus- ters and the optoelectronic performance. The formation of the perovskite microstructure features characteristics of both classical and non-classical growth mechanisms. The insights into perovskite thin-film growth developed by the present study provide clear implications for the development of future hybrid perovskite microstructures.

Solution-processed quantum-dot light-emitting diodes combining ultrahigh operational stability,shelf stability,and luminance

The shelf-stability issue,originating from the ZnO-induced positive aging effect,poses a significant challenge to industrializing the display technology based on solution-processed quantum-dot light-emitting diodes(QLEDs).Currently,none of the proposed solutions can simultaneously inhibit exciton quenching caused by the ZnO-based electron-transporting layer(ETL)and retain other advantages of ZnO.Here in this work,we propose a bilayer design of ETL in which a buffer layer assembled of SnO_(2) nanoparticles(NPs)suppresses the QD-ETL exciton quenching and tunes charge balance while ZnO NPs provide high electron conductivity.As a result,the bottom-emitting QLED combining capped ZnO and SnO_(2) buffer exhibit a maximum luminance over 100,000 cd m^(−2) and a T95 operational lifetime averaging 6200 h at 1000 cd m^(−2) on the premise of entirely inhibiting positive aging.