Du970p

The electroluminescence spectra were obtained using a Kymera-328I spectrograph and a Si EMCCD purchased from Andor Technology (DU970P), and a InGaAs CCD camera (DU491A-1.7, Andor Technology). Injection current used for EL was 1 mA. To determine EQE_EL, we first performed electroluminescence measurements, and found that the emission peaks are at 1.3–1.4 eV (Supplementary Fig. 22), for all of the active layers studied in this work. Then, we determine EQE_EL using a homebuilt setup using a Keithley 2400 to inject current to the solar cells. Emission photon-flux from the solar cells was recorded using a Si detector (Hamamatsu s1337-1010BQ) and a Keithley 6482 picoammeter.

The LQUMs were characterized using the same optical setup employed for fabrication. The LQUMs were pumped and observed using the same objective lens. Before observation, the emission was filtered by a short-pass filter (95% transmittance at 400–745 nm, Chromafilter, ET750sp-2p8). The emission spectrum was measured by an EMCCD (Andor, DU970P) equipped with a spectrograph (Andor, Shamrock 303i). With a grating of 1200 lines mm⁻¹ (centered at 500 nm), the spectral resolution achieved by our setup was 0.12 nm (confirmed by a 532-nm laser with a linewidth of 0.28 pm). The emissive spot of the LQUM was precisely selected by an entrance slit of 20 μm to yield pure laser emission. A half-wave plate (Thorlabs, WPH10M-980) and a birefringent polarizer (Thorlabs, GL 10) were installed before and after the excitation, respectively, to investigate the transverse modes and the polarization of the laser emission.