Dopant-free materials for carrier-selective passivating contact solar cells: A review

The basics of dopant-free materials used as carrier-selective layers at the surfaces and interfaces in c-Si or poly-Si solar cells have been reviewed. Emphasis has been given to the discussion of a host of transition metal oxides (TMOs) having wide range of band structures and which have the carrier selective property of allowing only one type of carrier (electron or hole) to flow across their junctions with Si. The fabrication process of these materials are benign and at low temperatures which make them gradually attractive over the doped Si layers which need toxic materials and/or high temperatures for their formation. Silicon solar cells having dopant-free carrier selective TMOs fabricated by various groups using different fabrication processes and different contact configurations (Full area contacts, Partial area contacts or Interdigitated back contacts) have been reviewed and presented alongwith their photovoltaic performance. Different passivation schemes (full area or partial area) that could be used alongwith these dopant-free carrier selective materials have also been discussed.

Automated summary

This review article provides an overview of dopant-free materials used as carrier-selective layers in c-Si or poly-Si solar cells. The focus is on transition metal oxides (TMOs) that possess a wide range of band structures and exhibit carrier selective properties. These materials have the advantage of being fabricated at low temperatures, making them more attractive than doped Si layers which require toxic materials and/or high temperatures for their formation. The article also discusses various silicon solar cells fabricated with dopant-free carrier selective TMOs by different research groups, along with their photovoltaic performance. Different passivation schemes using these materials are also explored.