The Compound Effect of Mg and Tris(2-aminoethyl)amine for Long-Term Phase Stability in the γ-CsPbI₃ Perovskite Film

Despite the good thermal stability and suitable band gap witnessed in fully inorganic CsPbI 3 perovskites, their use in photovoltaic devices is limited due to the lack of long-term phase stability in an ambient environment. Therefore, we demonstrate an effective way of improving long-term ambient and thermal stability along with enhancement in the optoelectronic properties of CsPbI 3 thin films. Here, we have shown that the incorporation of Mg and tris(2-aminoethyl)amine (TAEA) in CsPbI 3 results in a tremendous increase in thermal as well as ambient stability. It is noted that the presence of both TAEA and Mg is critical for the stabilization of the photoactive black phase of CsPbI 3 . The TAEA-containing CsPb 1– x Mg x I 3 film is found to be stable for more than 7 months when exposed to continuous heat at 85 °C in an ambient N 2 atmosphere. The optimized CsPb 0.85 Mg 0.15 I 3 film containing TAEA is detected to showcase the superior optoelectronic properties along with greatly enhanced ambient stability of more than 20 days in RH∼60–70%.