Publications by authors named "Gwisu Kim"

In perovskite solar cells, the interfaces between the perovskite and charge-transporting layers contain high concentrations of defects (about 100 times that within the perovskite layer), specifically, deep-level defects, which substantially reduce the power conversion efficiency of the devices. Recent efforts to reduce these interfacial defects have focused mainly on surface passivation. However, passivating the perovskite surface that interfaces with the electron-transporting layer is difficult, because the surface-treatment agents on the electron-transporting layer may dissolve while coating the perovskite thin film.

View Article and Find Full Text PDF

High-efficiency lead halide perovskite solar cells (PSCs) have been fabricated with α-phase formamidinium lead iodide (FAPbI) stabilized with multiple cations. The alloyed cations greatly affect the bandgap, carrier dynamics, and stability, as well as lattice strain that creates unwanted carrier trap sites. We substituted cesium (Cs) and methylenediammonium (MDA) cations in FA sites of FAPbI and found that 0.

View Article and Find Full Text PDF
Article Synopsis
  • The study focuses on improving the stability and efficiency of the α-phase of formamidinium lead triiodide (FAPbI) for use in perovskite solar cells by using methylenediammonium dichloride (MDACl) as a doping agent.
  • This method resulted in a certified short-circuit current density of 26.1 to 26.7 mA/cm² and power conversion efficiencies (PCEs) of 23.7%.
  • Notably, the unencapsulated solar cells maintained over 90% of their initial efficiency after extensive testing under harsh conditions, demonstrating superior thermal and humidity stability compared to devices stabilized using conventional methods.
View Article and Find Full Text PDF

Over the last several years, inorganic-organic hybrid perovskites have shown dramatic achievements in photovoltaic performance and device stability. Despite the significant progress in photovoltaic application, an in-depth understanding of the fundamentals of precursor solution chemistry is still lacking. In this review, the fundamental background knowledge of nucleation and crystal growth processes in solution including the LaMer model and Ostwald ripening process is described.

View Article and Find Full Text PDF