Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container, also including at least one small perovskite single crystal, and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows, in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate. For example, a top portion of the substrate external to the solution may be cooled.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with Government support under contract DE-EE0006709 awarded by the Department of Energy (DOE), and under contract HDTRA1-14-1-0030 awarded by the Defense Threat Reduction Agency (DTRA). The Government has certain rights in this invention.