Efficient silicon solar cells with dopant-free asymmetric heterocontacts
Light JV characteristic and schematic of the dopant-free asymmetric heterocontact (DASH) silicon solar cell showing a conversion efficiency of 19.4%, with a high Voc above 710 mV, has been achieved at the proof-of-concept stage. TCO refers to a Transparent Conductive Oxide stack.
Demonstration of efficient crystalline silicon solar cells without the use of doped-silicon layers or regions.
Significance and Impact
Commercially available crystalline silicon solar cells utilize doped-silicon layers or regions to separate photo-excited carriers and hence deliver power. This approach demonstrates that high efficiencies can be achieved using metal oxide and alkali metal fluoride as dopant-free carrier-selective contacts overcoming a number of fundamental and practical limitations.
- LiFx/Al and MoOx heterocontacts are utilized due to their significant asymmetry in work function (2.8 eV vs 5.7 eV) which assists in carrier separation at the two surfaces.
- Thin passivating hydrogenated amorphous silicon layers are implemented under the selective layers to enhance the voltage.
- These heterocontacts are integrated into a simplified DASH cell—the first-of-its-kind to demonstrate efficiencies competitive with conventional processes.