and confirmed by NREL (National Renewable Energy Laboratory, US), IMEC
has succeeded in demonstrating a record conversion efficiency of 24.7
percent from a single-junction GaAs cell, grown epitaxially on a Ge
substrate. The record results are part of the ESA-IMAGER project in
which IMEC is involved (see correction below).
The focus of the project is to develop a hybrid monolithic/mechanically-stacked triple-junction solar cell that consists of III-V materials as the top cells with Ge cells making up the bottom of a concentrator-based PV solution. The aim is to reach 35 percent plus conversion efficiencies.
The record cell measures 0.25cm², and shows an efficiency of 24.7%, with an open-circuit voltage (Voc) of 999 mV, a short-circuit current (Jsc) of 29.7 mA/cm², and a fill factor of 83.2 percent. The cell was made under the ESA-IMAGER project.
* Correction: We incorrectly reported in this
story that the development of a hybrid monolithic/mechanically-stacked triple
junction solar cells was under the ESA-IMAGER project. However, IMEC has
informed us that this aspect only relates to the 24.7 percent single junction
GaAs cell recorded measurements. IMEC is heading its own developments in
respect to III-V materials based solar cell research.