Efficient Rec. 2020 Compliant Pure‐Green Mixed‐Cation Perovskite Light‐Emitting Diodes With Multifunctional Co‐Additives

Abstract Perovskite light‐emitting diodes (PeLEDs) compliant with Rec. 2020 standards have raised increasing attention for next‐generation displays. As a class of pure‐green emitters, the mixed‐cation FA x Cs 1‐x PbBr 3 perovskites exhibit compatible band emission, but suffer from inferior luminescence performance. The approach to tackling this issue is hindered by a lack of in‐depth understanding of their crystallization manipulating mechanism. This work unveils the crystallization process of mixed‐cation FA 0.7 Cs 0.45 GA 0.1 PbBr 3 perovskites, demonstrating the fast spontaneous growth readily induces severe crystal defects accompanied by poor charge confinement. This motivates us to introduce additional kinetic barriers to manipulate the perovskite crystallization via the synergistic co‐additives of 3‐((2‐(methacryloyloxy)ethyldimethyl)ammonio)‐propane‐1‐sulfonate (DMAPS) and 1,4,7,10,13,16‐hexaoxacyclooctadecane (crown). The multifunctional groups in the co‐additives afford robust chemical affinities with the diverse organic and inorganic precursor ions simultaneously, which enable decent nanograin growth with effective crystal defect healing and charge confinement. Ultimately, mixed‐cation FA 0.7 Cs 0.45 GA 0.1 PbBr 3 perovskites with a high photoluminescence quantum yield of 96% are achieved. The resultant pure‐green PeLEDs with the Rec. 2020 compliance exhibit a champion external quantum efficiency (EQE) of 31.89%, average EQE of 29.5%, maximum luminance of 2 × 10 5 cd m −2 and operational half‐lifetime of 3.2 h at an initial luminance of 7000 cd m −2 (extrapolated: ≈3500 h at 100 cd m −2 ).