Integration　of　electrical　switching　and　light　emission　in　a　single　unit　makes　organic　light-emitting　transistors　(OLETs)　highly　promising　multifunctional　devices　for　next-generation　active-matrix　flat-panel　displays　and　related　applications.　Here,　high-performance　red　OLETs　are　fabricated　in　a　multilayer　configuration　that　incorporates　a　zirconia　(ZrOx)/cross-linked　poly(vinyl　alcohol)　(C-PVA)　bilayer　as　a　dielectric.　The　developed　organic/inorganic　bilayer　dielectric　renders　high　dielectric　constant　as　well　as　improved　dielectric/semiconductor　interface　quality,　contributing　to　enhanced　carrier　mobility　and　high　current　density.　In　addition,　an　efficient　red　phosphorescent　organic　emitter　doped　in　a　bihost　system　is　employed　as　the　emitting　layer　for　an　effective　exciton　formation　and　light　generation.　Consequently,　our　optimized　red　OLETs　displayed　a　high　brightness　of　16　470　cd　m(-2)　and　a　peak　external　quantum　efficiency　of　11.9%　under　a　low　gate　and　source-drain　voltage　of　-24　V.　To　further　boost　the　device　performance,　an　electron-blocking　layer　is　introduced　for　ameliorated　charge-carrier　balance　and　hence　suppressed　exciton-charge　quenching,　which　resulted　in　an　improved　maximum　brightness　of　20　030　cd　m-2.　We　anticipate　that　the　new　device　optimization　approaches　proposed　in　this　work　would　spur　further　development　of　efficient　OLETs　with　high　brightness　and　curtailed　efficiency　roll-off.