In this work, p-n junctions were fabricated at low temperature by means of UV-assisted thermal annealing. At 200 °C, remarkable rectifying and optical properties were observed due to the conversion of the sol-gel precursors to oxide films, which was aided by UV exposure. The resulting p-NiO/n-ZnO structures are featured as the thinnest ever reported (≈55 nm) based on a solution process with a large forward electrical current 10 −2 -10 −1 A cm −2 and the lowest leakage current (1 μA cm −2 ). UV light and precursor solution engineering contributed to form metal-oxide bonding at relatively low temperature in ambient conditions. The heterojunctions fabricated by the proper combination of these alternatives and simple processes were evaluated using UV-vis and FT-IR spectroscopy, FE-SEM, AFM, XRD, XPS, and I-V curves.

Previous studies successfully produced conductive thin films from organo‐metallic‐compounds‐based inks. Some inks like those made from copper salt and amines, however, tend to move during thermal annealing and, thus, affect the conductive pattern on the substrate. In this study, conductive inks were synthesized by forming complexes of copper with amines and/or blended amines. To build‐up an organo‐metallic framework and preserve the pattern throughout the annealing period, diamine was added to the complex in different proportions. The prepared inks were coated on glass substrate and were annealed on a hot plate at 170°C under the gaseous mixture of formic acid and alcohol for 5 min. The metallic film was observed to retain the original pattern of the ink during and after annealing. Adhesion on the substrate was also improved. Inks with blended amines produced films with lower resistivities. The lowest electrical resistivity recorded was 4.99 μΩ cm, three times that of bulk copper.