Perovskite Light-Emitting Diodes (PeLEDs) represent a highly promising LED technology due to their exceptional color purity, tunable emission color, and low manufacturing cost. However, the current record external quantum efficiency (EQE) for PeLEDs is limited to 32\%, still below the 40\% achieved by organic LEDs (OLEDs). This limitation primarily stems from defects within the perovskite layer and at interfaces between different layers in the device. Effective passivation of these defects is essential for further advancing PeLED efficiency.

In this thesis, we established the first operational PeLEDs within the PVMD group, leveraging its perovskite solar cell production line. We developed the fabrication process from the ground up and characterized the resulting device performance.

The first part of this thesis addresses the stability of perovskite layers during optical testing in ambient air. We observed that carrier lifetime measurements depend heavily on the perovskite's exposure time to air and the presence of protective overlayers, rather than solely on its inherent optoelectronic properties. This instability arises from rapid perovskite degradation in air. To mitigate this, we employed spin coating to deposit a protective PMMA layer over the perovskite and optimized this coating process. Characterization confirmed that PMMA significantly slows degradation. Additionally, we identified and corrected alignment issues in the photoluminescence quantum yield (PLQY) measurement setup, which had introduced substantial uncertainty. We refined the PLQY testing procedure to enhance result reliability.

The second part focuses on developing a quasi-2D perovskite emissive layer (EML) with low bulk defect and superior optical properties. Based on quasi-2D perovskites (PEA2(FAPbBr3)n−1PbBr4) typically exhibit better emission characteristics than bulk counterpart (FAPbBr3) We first confirmed the phase composition of our synthesized perovskite, verifying the formation of quasi-2D perovskite with the targeted phase distribution (n = 3). We then introduced two additives: [2-(9H-Carbazol-9-yl)ethyl]phosphonic Acid (2PACz) and KBr to enhance the optoelectronic property of EML. Photoluminescence (PL) testing revealed that 2PACz significantly enhances PL intensity, while KBr showed no such effect. Subsequently, we applied different antisolvents to improve perovskite film morphology. Results demonstrated that ethyl acetate yielded the highest PLQY. Our champion quasi-2D perovskite sample achieved a PLQY of up to 49\%.

The third part details the development and characterization of carrier transport layers for PeLEDs. For the electron transport layer (ETL), we employed 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) and used simulations to study how its thickness affects optical performance. Simulations indicated negligible performance variation for TPBi thicknesses between 40 nm and 80 nm. For the hole transport layer (HTL), we fabricated a self-assembled monolayer (SAM) HTL using [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic Acid (MeO-2PACz) and [4-(3,6-Dimethoxy-9H-carbazol-9-yl)butyl]phosphonic Acid (MeO-4PACz), which could reduce interfacial defect at HTL/ETL interface. However, devices with this SAM-HTL structure didn't emit light during voltage sweeps and exhibiting low turn-on voltages in J-V characteristic. We attribute this to electrical breakdown caused by electron tunneling through the extremely thin (1-2 nm) SAM layer. To suppress tunneling, we introduced an underlying NiO$_{x}$ layer. This modified structure demonstrated to be successfully prevented tunneling and enabled functional PeLEDs. To further optimize hole transport while minimizing thickness, we modeled the relationship between HTL thickness and electron tunneling probability. Calculations revealed that increasing the HTL thickness by approximately 3 nm effectively shields against tunneling. This optimized, ultra-thin HTL design paves the way for PeLEDs operating at low voltages with state-of-the-art optical performance.