Organic-inorganic nanocomposites consisting of electroactive conjugated polymer, poly(3-hexylthiophene) (P3HT) tethered on the surface of semiconductor CdSe quantum dot (i.e., P3HT-CdSe nanocomposites) at the air/water interface formed via Langmuir isotherms were explored for the first time. The P3HT-CdSe nanocomposites displayed a high pressure plateau (∼10.5 mN/m) in the Langmuir isotherm, illustrating their complex packing at the air/water interface. The packing of the Langmuir-Blodgett (LB) depositions of nanocomposites was revealed by AFM measurements. Furthermore, photovoltaic devices fabricated from the LB depositions exhibited a relatively high short circuit current, ISC, while maintaining a thin film profile. These studies provide insights into the fundamental behaviors of semiconductor organic-inorganic nanocomposites confined at the air/water interface as well as in the active layer of an organic-based photovoltaic device.