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intense panchromatic absorption [4] and high charge carrier mobilities. [5] In addition, their band gap can be easily tuned by simple variation of their ionic composition. [6] For example, a mixed-ion perovskite obtained as a mixture of formamidinium (FA) lead iodide and methy lammonium (MA) lead bromide, [FAPbI 3 ] 0.85 [MAPbBr 3 ] 0.15 , delivered the best to date energy conversion efficiencies of over 21% and revealed promising stability and reproducibility. [7-9] All the above mentioned, together with the ambipolar charge transport characteristics of perovskites, [10] are exceptional properties behind the high efficiency reported in literature. However, highly efficient PSCs are mostly achieved when sandwiching the perovskite film between an electron-transport layer (ETM, n-type) and a hole-transport layer (HTM, p-type), to enhance the selective blocking and extraction of charges into the external circuit. In this connection, using mesoporous or planar metal oxide ETM, such as TiO 2 , delivered the best results. [11] In terms of HTM, small molecules and polymers have shown impressive performances, being so far 2,2′,7,7′-tetrakis(N,N-dip -methoxyphenylamin e)-9,9′-spirobifluorene (Spiro-OMeTAD) [12] and poly(triaryl-amine) (PTAA) [13]