To address this challenge, we integrated an additional ETL, 1,3,5-Tri(m-pyridin-3ylphenyl)benzene (TmPyPB), between the perovskite and TPBi layers. TmPyPB, known for its electron-deficient pyridine moieties, serves as an effective electron-transport and hole-blocking layer in various organic electronic devices. Its lower HOMO level of 6.7 eV is compatible with the valence band maximum of PEA2PbCl1Br3, thereby enhancing hole-blocking efficiency within the dual ETLs device stack. Furthermore, TmPyPB's wider bandgap of 4.0 eV mitigates the spectral overlap with the perovskite emission. For the modified device architecture, we employed a dual-layer ETL comprising of 20 nm of TmPyPB and 20 nm of TPBi, as shown in Figure , as compared to 40 nm of TPBi in Figure . The Figure device architecture led to a considerable reduction in current density at operational voltages, as evidenced by the current density measurements in Figure ; at 5V, the TmPyPB/TPBi device exhibited a current density of an order of magnitude lower than that of the TPBi device. The EL spectra, depicted in Figure , reveals that the TmPyPB/TPBi device produces a sharp perovskite emission peak at 399 nm, in contrast to the broad emission spectrum encompassing both TPBi and perovskite for the TPBi-only device architecture (Figure and). The strategic replacement of part of the TPBi layer with TmPyPB effectively suppresses exciton formation in the TPBi layer and promotes exciton recombination within the perovskite layer, culminating in the observed clean, single-peak EL emission. Optical measurements were also employed to further analyze the influence of different device architectures on the optical properties of the perovskite. As depicted in Figure , three distinct device structures-ITO / PEDOT: PSS / Perovskite, ITO / PEDOT:PSS / Perovskite / TmPyPB / TPBi, and ITO / PEDOT: PSS / Perovskite / TPBi -exhibited identical PL spectra when excited with a 365 nm lamp. To delve deeper, time-resolved photoluminescence (TRPL) was conducted using a 379 nm pulsed laser to excite the devices, where the 393 nm emission was monitored. Note that TPBi PL was not observed under 365 nm or 379 nm excitations. The TRPL data, presented in Figure alongside the instrument response function (IRF), were modeled using a bi-exponential decay function: