Perovskite solar cells with 2-step inter diffusion by controlling composition engineering

Abstract

Perovskite materials have several properties, including tunable optical bandgap, high charge carrier mobility, and high photoluminescence quantum efficiency (PLQE). There are several ways to achieve high efficient perovskite solar cells; one step dropping method and two–step inter–diffusion method. The one–step method is efficient, but due to the cell uniformity critical for commercialization, it is not suitable for large area methods. On the other hand, perovskite solar cells using the two–step method have a more uniform morphology, which is advantageous for large–area solar cells. Large–area processing methods include co–evaporation methods and slot die, but are expensive. For commercialization, stability is as important as large–area perovskite solar cells. Since pure MAPbI3 perovskite solar cells are less stable because they contain organic methyl ammonium ion (MA+) in the perovksite structure. To overcome this problem, there are many efforts to exchange pure organic cations with inorganic counterparts such as cesium ions. In this paper, large area and sustainable perovskite solar cells were fabricated by combining 2–step method and Cs–substituted perovskite solar cell, sequentially, which obtains simultaneously large area and high efficiency.