Following the success of the first, second & third OTF conferences in Chicago, Cancun & Rome which took place in July 2014, March 2015, July 2017 we are delighted to be organising a fourth series. Complex oxide thin films are finding applications in a wide range of energy and information technologies, including electron and ion conductors, photovoltaics, thermoelectrics, dielectrics, and resistive switching. Irrespective of whether single thin films or more sophisticated multilayered systems are employed, each of these technologies requires a thorough knowledge of the oxide physicochemical properties, its interactions with the environment and the role of defect/interface/boundary effects that might stem between film and substrate, layers with different compositions or even simply from the grain boundaries. Whilst depending on the technology area the key properties might be different, many of the materials optimization strategies may be common. Therefore, we believe that the discussion between diverse and even complementary researchers’ communities can be extremely beneficial for a better understanding of the crucial aspects that need to be addressed to improve materials properties. The purpose of this meeting is hence to foster the exchange of ideas between the relevant energy and information themes with the overall aim of sparking extensive discussions of the advances that materials physics and chemistry can make in thin film applications.