Improved photoemission and stability of 2D organic-inorganic lead iodide perovskite films by polymer passivation.

2D organic-inorganic lead iodide perovskites hold great promise for functional optoelectronic devices. However, their performances have been seriously limited by poor long-term stability in ambient environment. Here, we perform a systematic study for the stability improvement of a typical 2D organic-inorganic lead iodide perovskite (PEA)PbI. The degradation of the (PEA)PbI films can be attributed to the interaction with the humidity in environment, which leads to decomposition of the perovskite components. Then, we demonstrate that polymer passivation provides an effective approach for improving the crystal quality and stability of the (PEA)PbI films. Correspondingly, the photoemission of the polymer-passivated (PEA)PbI films has been enhanced due to the decreased trap states. More importantly, a hydrophobic polymer (Poly(4-Vinylpyridine), PVP) will protect the (PEA)PbI films from humidity in ambient environment, which can greatly improve the physical and chemical stability of the 2D perovskite films. As a result, the PVP-passivated (PEA)PbI films can produce a bright emission even after long-term (>15 d) exposure to ambient environment (25 °C, 80% RH) and continuous UV illumination. This work provides a convenient and effective approach for improving the long-term stability of 2D organic-inorganic lead iodide perovskites, which shows great promise for fabricating large-area and versatile optoelectronic devices.