|
Organic-inorganic perovskites have emerged as an interesting class of materials that have excellent photovoltaic properties for application to solar cells. The power conversion efficiency of perovskite solar cells over 20% has already been realized through systematic optimization of materials and fabrication processes. However, the long-term stability of perovskite solar cells still need to be improved for practical applications. In this study, we introduced a multifunctional benzoquinone (BQ) additive into a precursor solution containing methylammonium iodide (MAI) and lead iodide (PbI2) used for spin-coating of perovskite films. Resulting spin-coated perovskite films containing BQ had the improved perovskite morphology and crystal quality because of intermolecular interaction between MAI and BQ slowing the rate of perovskite crystal formation. Therefore, we obtained the greatly enhanced power conversion efficiency from 10.7% to 15.6%. The reduced charge recombination loss by electron transfer from perovskite to BQ is another source of the improved efficiency. In addition to the efficiency enhancement, the BQ addition led to the extended lifetime about twenty-six times. The lifetime, at which efficiency reduces to 80% of the initial under the one-sun condition (100 mW/cm2 and AM1.5G), reached about 4000 h, one of the longest lifetimes ever reported in perovskite solar cells. The extended lifetime can be explained by the reduced formation of carrier traps originating from metallic lead during solar irradiation as the results of thermally stimulate current measurements. We believe that the present findings offer insight to help obtain efficient, stable organic-inorganic perovskite solar cells for future applications.
|
