Recently, we have studied photoelectrochemical properties of films of nanodiamond (ND)-regioregular polyhexylthiophene (RRP3HT), ND-poly(3-dodecylthiophene), polyaniline, and other derivatives of polythiophene. The ND-RRP3HT, BN-RRP3HT and microdiamond (MD)-RRPHTH films were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction techniques, respectively. The short circuit current, fill factor, and power conversion efficiency (PCE) for MD-RRP3HT, ND-RRP3HT and hexagonal boron nitride (hBN)-RRP3HT films were compared. The ND-RRP3HT nanostructured film revealed 8 to 20 times more photocurrent than most other nanostructured RRP3HT films in a photoelectrochemical cell. The ND-RRP3HT and hBN-RRP3HT films revealed improved efficiency compared to the MD-RRP3HT film. Due to the increased band gap, the hBN-RRP3HT have a higher PCE than ND as well as MD films. ND-RRP3HT and hBN-RRP3HT hybrid films exhibited comparable photoelectrochemical properties. (C) 2016 Elsevier B.V. All rights reserved.