Fig. 1. Structure of the device and basic properties. (a) Schematic structure architecture; (b) cross section scanning electron microscope (SEM) image of the device; (c) normalized emission (blue) and absorption (red) of prepared CsPbBr3 film; (d) refractive index of each layer and electric field distribution of the 530 nm optical standing wave inside device; (e) reflectivity of strongly coupled microcavity device at 0° and 33° relative to the normal direction; (f) PL intensity map of the cavity device with the area of 100  μm×100  μm.

Fig. 2. Angle-resolved reflectivity and analysis. (a) Angle-resolved reflectivity (black lines) of devices at three different normal cavity–exciton detunings: Δ=1.1, −77, −128  meV and angle-dependent shifts of reflection dips (orange lines). (b)–(d) UP (red) and LP (blue) dispersion curves of exciton–polariton, fitted with extracted angle-resolved reflectivity dips (*) and theoretical two-level model (solid lines). Dotted lines correspond to the dispersion of the bare cavity photon (gray) and excitonic (purple) modes. (e)–(g) Components of exciton (blue) and photon (red) in LP states at the three detunings.

Fig. 3. Optoelectronic performance of the device. (a)–(c) Angle-resolved PL/EL spectra of the three detunings. UPs, LPs, Ex, and Eph dispersions from fitted ARR in Fig. 2 are marked simultaneously. (d) Energy-level diagram of the as-fabricated device; (e), (f) comparison of current density(J)-voltage(V)-luminance(L)-external quantum efficiency (EQE) curves (inset: photograph of perovskite exciton–polariton LED at operation); (g) spectral stability of the −77  meV detuning device under different current densities; (h) distribution of peak EQE for −77  meV detuning devices; (i) operational stability of the −77  meV detuning device under constant current measured with an initial max luminance of 700  cd/cm2.

Fig. 4. Influence of MAA electrode thickness on device performance. (a) Angle-resolved reflectivity of devices with 20 and 40 nm MAA as top electrodes; (b), (c) angle-resolved PL/EL of devices with 20 and 40 nm MAA as top electrodes; (d), (e) J-V-L-EQE characteristics; (f) normal EL spectra with 20 and 40 nm MAA electrodes.

Fig. 5. Fabrication process of our perovskite polariton LED.

Fig. 6. Schematic diagram of normal reflection detection.

Fig. 7. Additional reliability data of device fabrication. (a) Reflection of TiO2/SiO2 substrate. (b) Edge of ITO film sputtered with a 0.1 mm thick mask. (c) XRD pattern for the prepared CsPbBr3 film. (d) AFM topography image of the prepared CsPbBr3 film. The root mean square (RMS) roughness is 1.737 nm. (e) Temperature-dependent photoluminescence of prepared CsPbBr3 film; the inset is a photograph of prepared CsPbBr3 film under UV light illumination. (f) Integrated photoluminescence intensities are fitted by I(T)=I0/(1+A⋅exp(−Eb/KT)) [47,48]. Exciton binding energy is extracted from fitting parameter Eb. (g)–(i) PL spectra of x direction and y direction square subregions.

Fig. 8. (a), (b) J-V-L-EQE characteristics of reference LED without microcavity. (c) Current density versus voltage curves of hole-only and electron-only devices.

Fig. 9. (a) Simulation of bare cavity reflectivity. The FWHM of cavity mode is 36 meV. (b) Comparison of simulated reflection of bare cavity with 20 and 40 nm MAA top electrode. (c) Simulated reflection of cavity mode with thickness of MAA from 10 to 50 nm.