Fig. 5: Wavelength tunability and spectral stability.
From: Suppressing phase disproportionation in quasi-2D perovskite light-emitting diodes
a, b EL spectra (a) of PPT based quasi-2D perovskite LEDs with different compositions and the corresponding CIE coordinates (b). Typically, <n > = 3 represents that the stoichiometric ratio of precursor solution follows the general chemical formula of (PPT)2FAn−1PbnI3n+1 with a nominal n = 3. c The relationship of EQEs against EL peaks. d, e Time evolution tracking of EL spectra for LEDs fabricated from <n> = 3 with 10% Br + 90% I (d), and <n> = 5 with 100% I (e) qausi-2D perovskites. The current density was maintained constant at 1 mA cm−2 during the measurement. The extraordinary spectral stability, where the EL spectra did not show obvious shift for both cases under long-term operation, demonstrates the great suppression of halide segregation and phase disproportionation, respectively.
