Additives in Halide Perovskite for Blue-Light-Emitting Diodes: Passivating Agents or Crystallization Modulators?
Nur Fadilah Jamaludin, Natalia Yantara, Benny Febriansyah, Yeow Boon Tay, Bening Tirta Muhammad, Shoba Laxmi, Swee Sien Lim, Tze Chien Sum, Subodh G. Mhaisalkar, Nripan Mathews
Abstract
Successful adoption of defect management and carrier confinement strategies in Ruddlesden–Popper (RP) perovskites has driven the impressive improvements to performance of perovskite-based light-emitting diodes (PeLEDs) seen to date. Although functional additives have been advantageous in mitigating defects, their influence over crystallization behavior of RP (L2Am–1PbmX3m+1) perovskites has yet to be fully studied. This is especially important for blue-emitting monohalide RP perovskites, where stringent control over m domain distribution is needed for efficient PeLEDs. Herein, we investigate the effect of triphenylphosphine oxide (TPPO) on crystallization behavior of blue RP (PBA2Csm–1PbmBr3m+1) perovskites. Despite TPPO addition, its absence in the resulting film eliminates its role as a passivating agent. Instead, TPPO acts as crystallization and phase distribution modulator─promoting the formation of a narrow distribution of higher m domains with higher Br content. In doing so, an enhancement of ∼35% was noted with the champion device yielding efficiency of 3.8% at λ of 483 nm.