Optical absorption driven by efficient refraction and light concentration for photovoltaic applications

Ankit Kumar, Ankit Chauhan, Jordi Llobet, Helder Fonseca, Patrícia C. Sousa, Carlos Calaza, Gil Shalev

Research output: Contribution to journalArticlepeer-review


Broadband absorption of the solar spectrum is a prerequisite to any photovoltaic technology. Subwavelength arrays are known to provide various mechanisms for broadband and omnidirectional absorption of the solar spectrum. In the current work we examine optical absorption in NP arrays decorated with SiO2 quasi-nanolenses (qNL arrays), which numerically exhibit 10–15 % increase in broadband absorption. Specifically, near-field scanning optical microscopy (NSOM) is employed to probe the underlying optical absorption mechanisms. Two NSOM methods are employed for the investigation: 1) far-field imaging using near-field excitation which allows the determination as to the origin of the reflected far-field photons, and 2) far-field excitation and near-field scanning to measure the lateral optical propagations in the arrays. We show that the enhanced optical absorption in qNL arrays is due to combination of three mechanisms: 1) each qNL serves as an effective anti-reflection coating, 2) the presence of qNLs increases the optical interactions between the adjacent dielectrics to conclude elevated levels of light trapping, and 3) the presence of qNL induces strong light concentration of the incoming radiation into the dielectric structures.

Original languageAmerican English
Article number112625
JournalSolar Energy Materials and Solar Cells
StatePublished - 1 Jan 2024


  • Broadband absorption
  • Light trapping
  • Nanopillar array
  • Near-field scanning optical microscopy (NSOM)
  • Subwavelength arrays

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Renewable Energy, Sustainability and the Environment


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