Mixed‐Ligand Chiral Quasi‐2D Perovskites for Standard and Deep Blue CP‐LEDs

Abstract This study presents the development of mixed‐ligand quasi‐2D perovskites ((2‐PEA)_x(R/S‐2‐BA)₂MA₁Cs₁Pb₃Br_10+x, x = 0.8, 1.6, 2.4) for circularly polarized light‐emitting diodes (CP‐LEDs). By utilizing the strong confinement effect of 2‐phenylethylammonium (2‐PEA) and the chirality of R/S‐2‐butylammonium (R/S‐2‐BA), room‐temperature circularly polarized luminescence (CPL) across the green to deep blue spectrum is achieved. The green CPL attributes to the transfer of spin‐polarized excitons while the blue CPL originates from direct excitation of luminescent phases with intrinsic chirality. Finally, green and blue CP‐LEDs under ambient are realized. Notably, standard and deep blue CP‐EL is achieved based on 0.8PEA/(R/S‐2‐BA)‐ and 1.2PEA/(R/S‐2‐BA)‐films with impressive electroluminescent asymmetry factors (0.122 and 0.175), highlighting the potential of chiral perovskites in CP‐LEDs and opening avenues for the development of room‐temperature full‐color CP‐EL display.