Improved performance of pure red perovskite light-emitting devices based on CsPb(Br1-xIx)3 with variable content of iodine and bromine

All-inorganic cubic α-CsPbI3 perovskite for red perovskite light-emitting device (PeLED) applications is suffering from a phase transition. Unstable black α phase tends to transit to yellow δ phase under ambient conditions, which results in poor performance of the CsPbI3-based PeLEDs. Partial replacement of iodine anion with a comparatively smaller bromine anion in the perovskite film can effectively adjust the Goldschmidt tolerance factor and stabilize the α-phase. A phase-stable CsPb(Br1-xIx)3 perovskite has been obtained at low annealing temperature of 50°C by tuning the iodine-to-bromine ratios. A PeLED with pure red emission based on the CsPb(Br0.43I0.57)3 perovskite has been demonstrated. The maximum luminance and efficiency were 2200cd/m2 and 0.38 cd/A, respectively. Moreover, the PTAA layer was introduced between the PEDOT:PSS and perovskite film to improve the surface morphologies of perovskite. As a result, red PeLEDs with a maximum luminance of 2765cd/m2 have been achieved.