Light in a solar cell

• we want to trap as much as possible light in the solar cell structures (but only that part of the spectrum which has higher energy than the energy band-gap of the semiconductor used)
• we want to absorb as much as possible light in the active parts/layers of solar cell structure (absorption of light in supporting inactive parts of the structures, such as in contact layers only leads to heating of the cell)
• absorbed light in active parts/layers of solar cell generates photo-current of the cell (active part of the cell present narrow region around the pn junction or the intrinsic layer (such as i-uc-Si:H in the figure nearby) in case of p-i-n structures of thin-film solar cells)

Aim of optical modelling and simulations

• to analyze and improve above mentioned optical circumstances in solar cells and photovoltaic modules
• to invent novel optical concepts based on simulation results supported by experiments

Motivation and meaning

• the trends of solar cells production are going in the direction of thinning the structures
• in solar cells with thin active layers light management and light trapping issues become very important
• especially in thin-film solar cells there still exists a high potential to improve light trapping in the structures – optimization of the existing concepts and development of novel solutions are important!
• implementation of simulation results and findings into lab solar cells and in photovoltaic modules in production

Research activities of LPVO

Modelling

• one-dimensional semi-coherent optical simulator SunShine (developed in LPVO, model description)
• two-dimensional optical simulator FEMOS (developed in LPVO, model description)
• the use of three-dimensional simulator MEEP (developed at MIT, USA, link)
• development and use of novel optical models and simulators (e.g. to study plasmonic effects in solar cell structures with metal nano-particles, developed in co-operation of LPVO with HZB Germany,model description)
• development of advanced combined optical models (e.g. geometrical optics + coherent model

Simulations

• 1-D optical simulations of thin-film solar cells (a-Si, uc-Si:H, Cu(In,Ga)Se2, CdTe, DSSC)
  Selected publication on a-Si:H/uc-Si:H solar cells
• 2-D optical simulations of thin-film Si solar cells with textured interfaces (an example of light scattering at periodically textured surface is shown in the figure on the right side)
  Selected publication on solar cells with periodic texturesperiodičnih tekstur
• 3-D optical simulations of solar cells with textured interfaces
  Report- comparison of 2-D and 3-D simulations

Research of advanced optical concepts

Selected topics (published in journals):

• Modulated photonic crystals
• Modulated textures
• Advanced optical concepts of CIGS solar cells
• White paint back reflectors

Contact persons

Janez Krc

Benjamin Lipovsek

Links

Services in the area of optical modelling and simulations

Projects

Co-operations