where A1 and A2 are the amplitudes for the PL decay time of 𝜏 1 and 𝜏 2 . I(t) is the intensity of the PL. The fitted parameters are summarized in Table . The PL decay of the perovskite / TPBi sample had a relatively short average PL lifetime ( 𝜏 𝑎𝑣𝑒 = 3.28 𝑛𝑠 ) than the perovskite-only sample (𝜏 𝑎𝑣𝑒 = 3.76 𝑛𝑠), indicating that TPBi introduced luminescence quenching for the perovskite. The perovskite / TmPyPB / TPBi sample, however, it showed the longest PL lifetime (𝜏 𝑎𝑣𝑒 = 4.04 𝑛𝑠) among the three samples in Table , implying that TmPyPB is more effective in mitigating nonradiative recombination, potentially due to its energy level alignment with the perovskite, which helps to confine charge carriers within the perovskite layer. Finally, we fabricated a series of dual ETL PeLEDs with the structure quartz / ITO / PEDOT: PSS / PEA2PbCl1Br3 / TmPyPB / TPBi / LiF / Al, as shown in Figure . Scanning electron microscopy (SEM) of the cross section of the device is shown in Figure . PEDOT: PSS was spin-coated on quartz ITO substrates, and the perovskite was spin-coated on top of PEDOT: PSS. The substrates were then transferred to a vacuum chamber for thermal evaporation where 20 nm of TmPyPB, 20 nm of TPBi, 2 nm of LiF and 100 nm of Al were thermally evaporated sequentially. More fabrication details can be found in the Methods section. According to the previous two-step annealing, we can also obtain 2D perovskite thin films with good coverage and crystallization, which was shown in atomic force microscopy (AFM) in Figure .