The TKI Urban Energy project RADAR, funded by the Dutch government, finishes with succesful integration of Solmates' Pulsed Laser Deposition layers integrated in silicon based solar cell devices.
The goal of the project was to develop new materials and solar cell manufacturing processes for high efficiency, bifacial solar cells with transparent passivating contacts, using two parallel approaches: (1) Start from transparent metal oxides, and make them more chemically stable by intentional doping and (2) Start from more chemically stable poly-Si contacts, and make them transparent by alloying with oxygen or carbon.
The TU Eindhoven spend effort on the development of novel (doped) metal oxides by ALD for passivating contact applications. Nb2O5 was found as a novel passivating contact material, whereas conductive ZnO/Al2O3 and POx/Al2O3 were found to yield state-of-the-art passivation of n+ surfaces. TU Delft developed more transparent O/C-alloyed poly-Si contacts and demonstrated a preliminary cell efficiency of 21.5%. At Solmates the development of Transparent Conducting Oxides (TCOs) and selective Transparent Metal Oxides (TMOs) by large area PLD was done, leading to succesful integration of such layers into actual solar cells. During consortium runs with ECN.TNO, the high compatibility of PLD was demonstrated by achieving an iVoc of 744 mV. The implementation of a thin AlOx interlayer below e-beam MoOx has led to a new moly-poly record of 18.2% for a 6 inch solar cell, made at ECN.TNO, that is thermally stable up to 230°C. Meanwhile, DST further developed their corona charging system (CCS), and successfully demonstrated its use for characterizing novel passivation schemes.