Self-Assembled Superacid Monolayers on c-Si Provide Exceptional Surface Passivation and Low Contact Resistivity


Ghasemi M., Maden C., Bektaş G., Tsoi K., GÜNBAŞ E. G., TOFFOLİ H., ...More

Solar RRL, vol.9, no.14, 2025 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 9 Issue: 14
  • Publication Date: 2025
  • Doi Number: 10.1002/solr.202500290
  • Journal Name: Solar RRL
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Compendex, Environment Index, INSPEC
  • Keywords: contact resistivity, density functional theory, nonafluorobutane sulfonic acid, solar cell, superacid, surface passivation
  • Middle East Technical University Affiliated: Yes

Abstract

Minimizing surface recombination is crucial for enhancing silicon solar cell passivation. Conventional dielectric materials require vacuum deposition and high-temperature annealing, increasing complexity and cost. This study explores Nonafluorobutane sulfonic acid (C4HF9O3S), a superacid, as a passivation layer for silicon solar cells. Unlike traditional dielectrics, it eliminates the need for vacuum processing or high-temperature annealing while offering excellent passivation. Results show that the superacid forms a self-assembled monolayer on silicon, improving passivation and enabling efficient charge extraction. N-type silicon coated with the superacid achieves an effective lifetime exceeding 8.5 ms, and when combined with Al, it forms an interface with a contact resistivity as low as 5.75 mΩ.cm2. Characterization and density functional theory (DFT) calculations confirm both chemical and field-effect passivation mechanisms, validating the monolayer's superior performance. When integrated into a full solar cell, the Nona layer enhances device performance, yielding a 3.05% absolute efficiency gain compared to the reference cell without Nona. This study introduces a cost-effective alternative to conventional dielectrics, simplifying processing while reducing production costs and CO2 emissions, paving the way for sustainable, high-efficiency silicon solar cells.