Multi-Dopant Engineering in Perovskite CsSnCl: White Light Emitter and Spatially Luminescent Heterostructure.

Bi/Te co-doped CsSnCl with dual emission spectrum (i.e., 450 and 575 nm) was achieved by a modified solution method, which can overcome the phase separation in the previous method for CsSnCl crystal growth. The two emission peaks arising from the two dopants Bi and Te have distinct photoluminescence (PL) lifetimes. Thus, the control of dopant ratio or PL delay time will regulate the PL intensity ratio between 450 and 575 nm peaks leading to adjustable emission color. The energy transfer between the two emission centers, which is confirmed by the optical spectra and PL lifetime, has a critical distance around 7.8 nm with a maximum of 50% transfer efficiency. The Bi/Te co-doped CsSnCl with superior stability in water and aqua regia was fabricated into a single-phase white light-emitting diode. In the meantime, various luminescent heterostructures were obtained by epitaxial CsSnCl crystal growth with different dopants, which can broaden the study of composition engineering in halide perovskites.