The aim of this study is to demonstrate a quantum dot (QD) based heterojunction with working diode behaviour. This involves three steps, (1) fabrication QD sized tin sulphide (SnS) nanoparticles, (2) development of a compact TiO₂ layer, (3) fabrication of a heterojunction by multi-layered structure. The colloidal synthesis process was used to prepare the SnS QDs. The size of the QDs was controlled by the addition of Trioctylphosphine oxide (TOPO) to the synthesis process.  HRTEM shows that the size of QDs around 1.7 nm which is much less than Excitonic Bohr’s radius of SnS (7 nm). FTIR confirms that TOPO is attached with QDs. The crystalline peaks from (120) and (111) planes in the powder X-ray diffraction spectrum conforms the SnS material. The photoluminescence spectra show emissions around 656 nm and 764 nm corresponding to 1.89 eV and 1.62 eV. The optical band gap of these nanoparticles from UV-Vis spectroscopy is 1.89ev. This band gap value is much higher than bulk SnS band gap value, confirming the quantum confinement nature of SnS QDs. The activation energy of dark conductivity of QD layers was estimated to be 0.86eV. A compact TiO₂ layer was prepared by hydrothermal method. XRD confirms the rutile phase of TiO₂. SnS QDs were coated on it by the spray pyrolysis method. Parallel electrodes with silver paste were led on top of QD film to make the electrical contact. Dark I-V confirms Schottky-type behaviour.  Sharp breakdown voltage is observed at 3.6V, and very little leakage current is observed as a reverse saturation current of the order of 10^-3 mA/cm² with high forward current density of 0.7mA at 1.5V with a barrier height of 0.697eV. These results confirm the formation of proper blocking contact.