High Energy Efficiency Group
High Performance from Topsil PV-FZ Silicon Substrates
The silicon wafer manufacturer, Topsil, has developed a PV grade FZ silicon material with a cost structure reported as close to standard CZ materials. At UNSW, the PERL (passivated emitter, rear locally-diffused) cells have been fabricated on these Topsil PV-FZ substrates with bright etched planar surfaces to test the quality of these substrates. The table below lists the performances of some of these cells.
ID
|
Voc (mV)
|
Jsc (mA/cm2)
|
FF (%)
|
Eff (%)
|
| Wp-04-4a | 707
|
37.0
|
82.2
|
21.5
|
| Wp-04-4b | 706
|
37.7
|
82.6
|
22.0
|
| Wp-04-5f | 702
|
38.0
|
82.6
|
22.0
|
| Wp-04-6f | 702
|
38.3
|
81.3
|
21.9
|
Performance of ZnS/MgF2 double layer antireflection coated planar PERL cells on Topsil’s PV-FZ substrates as measured at UNSW according to Sandia calibrated PERL cells under 100mW/cm2 global spectrum.
These planar PERL cells demonstrated very high Voc of 707 mV which is only a few millivolts below our record for double-layer AR coated cells. This result confirms that the Topsil PV-FZ materials have the same high quality as the best FZ materials.
These cells also gave very high current densities and high fill factors. If the surface was textured, the cells have potential energy conversion efficiencies well above 24%.