We demonstrate a functional method to achieve surface passivation and construct a two-dimensional (2D) layer on a three-dimensional (3D) perovskite, eliminating the need for subsequent annealing ...steps. A key process is the integration of a single methylammonium lead iodide (MAPbI3) crystal with butylammonium iodide (BAI) in tetrahydrofuran. Density functional theory calculations reveal that the synergy between BA+ cations and Pb–I octahedral structures enables the formation of a distinct 2D layered framework. MA+ and BA+ exhibit adsorption energies of −5.519 and −5.925 eV, respectively, at MA vacancies on the perovskite surface. This finding indicates that BAI passivation induces surface-healing effects, increasing surface and device stability. The I– components of BAI also replace imperfections at the perovskite interface, affording considerably reduced deep-level anomalies and mitigating nonradiative recombination. This theoretical perspective is supported experimentally via X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy. BAI passivation and 2D-BA2PbI4 capping lowers work functions for 3D perovskite surfaces, registering at approximately 0.158 and 0.173 eV, respectively, which are lower than those of the control 3D film. Within the 2D/3D perovskite configuration, 2D-BA2PbI4 capping considerably increases the open-circuit voltage in solar cells. In comparison, devices with BAI-enhanced interfaces show improved durability with promise for solar cell applications.
Solution proceessable organic light emitting diodes (LEDs) requires multilevel approaches to achieve high efficiency. Time-Dependept Density Fuctional Theory method is carried to predict the ...molecular parameters such as triplet energies (E T ) which are important to achieve high efficiency Organic LED. This will guide the material designs. Interfacial treatment at the anode and cathode can help improve the charge injection and charge balance. The use of Nafion to modify the workfunction of Pedot:PSS increased the device efficiency for the blue phosphorescent Organic LED while flourinated alcohol can be used to modify the cathode resulting almost double of efficiency for `super-yellow' poly-(p-phenylenevinylene) Orgnic LED. We also found out that the E T of the materials can be significantly influeced by the side groups and intermolecular distance. Multilayer Organic LED can be used to confine the recombination region resulting in little change of CIE-cordinate in a wide range of luminance. Solution processable Orgnic LEDs show great promise in lowering the manufacturing cost of Organic LEDs.
