Metal halides perovskites (MHPs) are becoming an evolutionary semiconductor system for optoelectronic applications including solar cells and light emitting diodes owing to their solution processability and superior photophysical properties. However, traditional three-dimensional (3D) MHPs also face the challenge of instability to moisture, which restrains the performance of related MHPs devices. One strategy to overcome the stability issue is hybrid low-dimensional MHPs, where the inorganic framework is connected in two-dimensional (2D) or one-dimensional (1D) manner.
Conventional low-dimensional MHPs are consisted of inorganic metal–halide anionic framework charge balanced with insulating aliphatic organic cations, forming type-I band structures. In this UROP project, we aim to design novel π-conjugated organics for the synthesis of hybrid donor–acceptor metal-halide perovskites. A band structure of type-II will be formed in these new MHPs, in which the energy level of the lowest unoccupied molecular orbital (LUMO) of organic molecules is lower than the conduction band (CB) of inorganic subunits. Therefore, the electron on the inorganic subunits can be transferred into the organic molecules upon photoexcitation, forming a charge transfer (CT) state. CT can give rise to novel photophysics which will be characterized by steady-state and ultrafast spectroscopic methods.