We have demonstrated the successful fabrication of multiple-layer colloidal quantum dot (CQD)-sensitized near-infrared (NIR) photovoltaic (PV) cells using the solution processable HgTe CQDs and poly-3-(hexylthiophene) (P3HT) as hole-conducting polymer. The cells showed a 3.6 fold enhancement in power conversion efficiency under NIR light illumination by the post-ethanedithiol chemical treatment. The performance enhancement was mainly ascribed to the improved interfacial contact between HgTe CQDs by elimination of oleic acid as capping ligand on the surface of HgTe CQDs. In addition, the HgTe CQD-sensitized PV cells could effectively detect weak NIR light and process over 1 kHz level signals.