Abstract:
In general, Perovskite solar cells (PSCs) have been easily degraded by moisture, high temperature, etc. Additional of inorganic cation, e.g. Cs⁺ has been introduced to explore more complex compositions which also enhances the device performance and stability. In this work, PSCs with mixed organic-inorganic cations - MA₁-xCsxPb(I₁-yBry) ₃, where MA is methy1-ammonium, are fabricated by using the two-step spin-coating process. The halide group is also a mixture of iodide and bromide for bandgap energy tuning. The PSCs of n-i-p type are based on FTO/cp-TiO₂/mp-TiO₂/Perovskite/Spiro-OMeTAD/Au architecture. The amount of Cs is varied with x=0.03, 0.05, 0.07 and 0.09, while the amount of Br is varied with y = 0.05, 0.10, 0.15 and 0.20. Morphologies of the perovskite layers are investigated under the variations of Cs and Br. The open-circuit voltage (Voc) is directly affected by the addition of Br. The best PSC obtained in this work has Voc = 1.04 V, Jsc = 23.4 mA/cm², fill-factor = 64.7% and power conversion efficiency = 15.7%.
