  Circularly polarized (CP) electroluminescence from organic light-emitting
diodes (OLEDs) has aroused considerable attention for their potential in future
display and photonic technologies. The development of CP-OLEDs relies largely
on chiral-emitters, which not only remain rare owing to difficulties in design
and synthesis but also limit the performance of electroluminescence. When the
polarization (pseudospin) degrees of freedom of a photon interact with its
orbital angular momentum, photonic spin-orbit interaction (SOI) emerges such as
Rashba-Dresselhaus (RD) effect. Here, we demonstrate a chiral-emitter-free
microcavity CP-OLED with a high dissymmetry factor (gEL) and high luminance by
embedding a thin two-dimensional organic single crystal (2D-OSC) between two
silver layers which serve as two metallic mirrors forming a microcavity and
meanwhile also as two electrodes in an OLED architecture. In the presence of
the RD effect, the SOIs in the birefringent 2D-OSC microcavity result in a
controllable spin-splitting with CP dispersions. Thanks to the high emission
efficiency and high carrier mobility of the OSC, chiral-emitter-free CP-OLEDs
have been demonstrated exhibiting a high gEL of 1.1 and a maximum luminance of
about 60000 cd/m2, which places our device among the best performing CP-OLEDs.
This strategy opens a new avenue for practical applications towards on-chip
microcavity CP-OLEDs.
