Sub-10 meV Light Emission from Chemically Controlled Donor-Acceptor Defect Pairs in Solution-Processed 2D Hybrid Perovskites

Low dimensional hybrid perovskites formed from solvated chemical precursors possess properties central to next generation optoelectronic technologies. In this presentation we highlight a materials synthesis method that controls light emission below the optical gap from defects in hybrid lead iodide self-assembled quantum wells (SAQWs). We change cation concentrations to control crystal growth, and drive the formation of lead iodide SAQWs whose sub-gap photoluminescence (PL) spectra range from possessing a single broad peak to featuring several significantly narrower peaks. Power dependent PL measurements suggest we form I^- vacancies predominantly in the presence of high cation concentrations, while significant densities of amine impurity-iodide vacancy defective donor-acceptor pairs form under lower cation concentrations. Furthermore, we find some the narrowband peaks characteristic of low cation materials correspond to nearly degenerate, bound excitons whose dephasing dynamics lead to sub-10 meV peak widths. These results indicate bulk chemical characteristics of materials synthesis can act as an effective means to control the formation of point defects whose light emission may be useful for next generation quantum optoelectronic and photonics technologies.