Enhanced perovskite materials for photovoltaic devices

A perovskite material comprising:

• a perovskite crystal lattice having a formula of CMX3;
• and
• bulky organic cations residing near a surface or a grain boundary of the perovskite crystal lattice and substituted in the perovskite crystal lattice, wherein the bulky organic cations are selected from the group consisting of butane-1,4-diammonium, octane-1,8-diammonium, bis(4-aminobutyl)-ammonium, and tris(4-aminobutyl)-ammonium, wherein at least one of the bulky organic cations residing less than 50 nm into the perovskite material crystal lattice from the surfaces or the grain boundaries of the perovskite material crystal lattice, and wherein a tail group of at least one of the bulky organic cations is not chemically connected to the surfaces or grain boundaries of the perovskite material, and wherein at least one of the bulky cations is substituted for least two C cations in the perovskite crystal lattice;
• wherein:
• C selected from the group consisting of methylammonium, and formamidinium;
• M is Pb;
• and
• X comprises one or more anions each selected from the group consisting of halides.