Electrical, Optical, and Structural Characteristics of CH₃NH₃PbI₃ Perovskite Light-Emitting Diodes

Electrical, optical, and structural characteristics of perovskite light-emitting diodes (PeLEDs) are investigated. The PeLED consisting of ITO/ZnO/MAPbI₃ (CH₃NH₃PbI₃)/spiro-OMeTAD/Ag structures shows a peak emission wavelength of 766 nm, turn-on voltage of 1.7 V, reverse breakdown voltage of −5.4 V, current efficiency of 1.5 × 10⁻⁴ cdA⁻¹, maximum luminance of 0.1 cdm⁻², and an external quantum efficiency of 0.2% at bias voltage of 3 V (or a current density of 617 mA cm⁻²). The PeLED also shows a significant output drop at higher bias voltage. According to the analyses of forward J–V curves and structural studies, this could be associated with the anomalously large ideality factor of 12.8 and the high series resistance of 2.8 Ω cm², that is, the leakage current through parasitic shunt path (possibly through pinholes in the perovskite) and accelerated Joule-heating result in a significant output degradation.