The unique attributes of the copper indium selenide compounds simplify processing of solar absorbers on large area substrates for specific photoelectrochemical and photovoltaic applications. This work focuses on the use of off-stoichiometric, ordered defect chalcopyrite compounds from the Cu2Se(In2Se3)(n) series (CISe), where n > 1, for a wider variety of energy conversion devices. The CISe compounds can avail of thermodynamic reaction control, for inexpensive synthesis of CISe compounds in a single step, from a single electrolyte. This approach leads to surprisingly stoichiometric CISe compositions over a wide range of process parameters. The paper sketches our work on CISe based devices, highlighting Dr. Adam Heller's impact on the early evolution of photoelectrochemistry. The CISe films offer potential to achieve high performance as well as easy manufacturability for a wide range of devices. They can be used to construct efficient and stable CISe-based photoelectrodes to drive the photoelectrolysis of water. Their unique opto-electronic properties enable the fabrication of next generation nanostructured solar cells that can maximize solar spectral conversion to electricity. (C) 2014 The Electrochemical Society. All rights reserved.