High-performance large-area quasi-2D perovskite light-emitting diodes

Serious performance decline arose for perovskite light-emitting diodes (PeLEDs) once the active area was enlarged. Here we investigate the failure mechanism of the widespread active film fabrication method; and ascribe severe phase-segregation to be the reason. We thereby introduce L-Norvaline to construct a COO--coordinated intermediate phase with low formation enthalpy. The new intermediate phase changes the crystallization pathway, thereby suppressing the phase-segregation. Accordingly, high-quality large-area quasi-2D films with desirable properties are obtained. Based on this, we further rationally adjusted films' recombination kinetics. We reported a series of highly-efficient green quasi-2D PeLEDs with active areas of 9.0 cm(2). The peak EQE of 16.4% is achieved in = 3, represent the most efficient large-area PeLEDs yet. Meanwhile, high brightness device with luminance up to 9.1 x 10(4)cdm(-2) has achieved in = 10 film. Performance of perovskite LED tends to decline as the active area increases, thus understanding the failure mechanism is paramount to surmount this limitation. Here, the authors report severe phase-segregation to be the cause, and introduce L-Norvaline to overcome it, as the result, highly-efficient 9.0 cm(2) green PeLED is realised.

Automated summary

The performance of perovskite light-emitting diodes tends to decline as the active area increases, with severe phase-segregation identified as the cause. The introduction of L-Norvaline to construct an intermediate phase has successfully suppressed the phase-segregation, resulting in highly-efficient large-area quasi-2D films.