Study of compensated Si in the context of the recycling of p-type substrates for n-type based solar cell architectures

Compensated silicon has long been a topic of interest in semiconductor physics due to the complex interactions between donors and acceptors. Today, the growing emphasis on circular manufacturing and end-of-life module recycling drives the attention toward n-type silicon, the current market standard. The possibility of reusing p-type feedstock from decommissioned modules compensated by donor addition could enable its integration into modern n-type architectures such as TOPCon, SHJ, and IBC. However, a key question remains open: does n-type compensated silicon (particularly when derived from recycled sources) exhibit the required optoelectronic quality for these advanced device structures? This work presents first answers to this question through a comparative study of two compensated silicon ingots: (i) an intentionally co-doped n-type ingot grown from conventional polysilicon; and (ii) a compensated ingot grown from recycled p-type material with phosphorus addition. The study aims to elucidate how dopant compensation affects key material parameters such as carrier lifetime and mobility, resistivity, and defect activity, thereby assessing its suitability for advanced n-type solar cell technologies. The results of this work confirm that recycled compensated silicon is a viable route toward high-efficiency n-type solar cells.