Establishing a Relationship between the Bandgap and the Structure in 2D Lead Halide Perovskite Semiconductors

Hybrid lead halide perovskites have been intensively investigated due to their structural diversity and outstanding optoelectronic properties. As emerging semiconducting materials, their bandgaps play a key role in regulating the performance. Qualitative correlations between the bandgap and structure have been uncovered; however, quantified relationships have not yet been established. Herein, we report a series of hydrogen-bonded quasi-Dion–Jacobson (DJ) perovskite semiconductors, [(HOOC n H 2 n –2 NH 3 ) 2 ]PbBr 4 ( n = 3–8), as a model system to set up a more clear relationship between the structural distortions and optoelectronic properties. When the n ranges from 4 to 8, the serial compounds are featured by distinctive hydrogen-bonded diammonium layers containing dimerized COOH linkers and balanced photoluminescent and photodetection properties. A linear relationship between the bandgap ( E g ) and two structural parameters ( D int and D d ) is set up, that is, E g = 2.694 + 0.004680 D int + 0.3109 D d, indicating the roles of both the interlayer distance and inorganic framework distortion. This work not only expands the typical DJ-type perovskites but also provides a deepened understanding of the relationship between the structures and optoelectronic properties.