Ge quantum dots (QDs) have been applied to increase the internal quantum efficiency (IQE) of photodetector up to 1500% at the 400 nm and are expected to benefit the performance of solar cell. We have successfully prepared Ge-QDs using plasma enhanced chemical vapor deposition (PECVD) that is fully compatible with the solar cell deposition process. Transmission electron microscope (TEM) and Atomic force microscope (AFM) images show that the QDs are similar to 14 nm in diameter. By adjusting deposition time, as well as H-2 dilution ratio and H-2-plasma treatment time, the Ge-QDs are optimized for the highest solar cell efficiency. It is found that the IQE is significantly improved, particularly for long wavelength spectrum (lambda > 500 nm), resulting in increased short circuit current density (Jsc) by 8.31% and increased solar cell efficiency. (C) 2017 Elsevier Ltd. All rights reserved.