Optoelectronic simulations for novel light management concepts in Cu(In,Ga)Se2 solar cells

Abstract

One of the trends making its way through the Photovoltaics (PV) industry, is the search for new application possibilities. Cu(In,Ga)Se2 (CIGS) thin film solar cells stand out due to their class leading power conversion efficiency of 23.35 %, flexibility, and low cost. The use of sub-µm ultrathin CIGS solar cells has been gaining prevalence, due to the reduction in material consumption and the manufacturing time. Precise CIGS finite-difference time-domain (FDTD) and 3D-drift diffusion baseline models were developed for the Lumerical suite and a 1D electrical model for SCAPS, allowing for an accurate description of the optoelectronic behavior and response of thin and ultrathin CIGS solar cells. As a result, it was possible to obtain accurate descriptions of the optoelectronic behavior of thin and ultrathin solar cells, and to perform an optical study and optimization of novel light management approaches, such as, random texturization, photonic nanostructures, plasmonic nanoparticles, among others. The developed light management architectures enabled to push the optical performance of an ultrathin solar cell and even surpass the performance of a thin film solar cell, enabling a short-circuit current enhancement of 6.15 mA/cm 2 over an ultrathin reference device, without any light management integrated.

Cu(In,Ga)Se2 based ultrathin solar cells: the pathway from lab rigid to large scale flexible technology

“…A broadband increase is observed for the stainlesssteel substrate. However, the light trapping effect evaluated through the inclusion of the obtained surface roughness in the solar cells architecture via 3D finite-difference time-domain optical simulations 46 , shows a lower JSC enhancement than the one measured. Thus, optical phenomena are insufficient to solely explain the difference between the JSC of the Flexible and the SLG based devices 47 .…”

Cu(In,Ga)Se2 based ultrathin solar cells the pathway from lab rigid to large scale flexible technology

“…A broadband increase is observed for the stainless-steel substrate. However, the light trapping effect evaluated through the inclusion of the obtained surface roughness in the solar cells architecture via 3D finite-difference time-domain optical simulations 41 , shows a lower J SC enhancement than the one measured. Thus, optical phenomena are insufficient to solely explain the difference between the J SC of the Flexible and the SLG based devices 42 .…”

Will ultrathin CIGS solar cells overtake the champion thin-film cells? Updated SCAPS baseline models reveal main differences between ultrathin and standard CIGS

“…6 a) show that the presence of an AR layer increases the J sc value by 1.9 mA/cm 2 , from 23.4 mA cm − 2 to 25.3 mA cm − 2 , respectively. Finally, additional steps to improve the cell antireflection properties may include a nanostructured TCO window layer with 2D triangular gratings and an optimized period [31], with the advantage of reducing front reflection losses for a wide range of incident light angles.…”

“…To further lower the fabrication costs and the material consumption in CIGS devices, as well as to increase the manufacturing throughput, researchers worldwide are undertaking efforts to develop ultrathin (~500 nm) CIGS solar cells [27,28]. However, some performance limitations hinder the full potential of ultrathin devices, such as insufficient light absorption [29][30][31][32] and rear interface recombination [33,34]. The first may be tackled with light management [29,31,[35][36][37][38] schemes, whereas the latter may be addressed with passivation strategies [33,34,36,39,40].…”

“…However, some performance limitations hinder the full potential of ultrathin devices, such as insufficient light absorption [29][30][31][32] and rear interface recombination [33,34]. The first may be tackled with light management [29,31,[35][36][37][38] schemes, whereas the latter may be addressed with passivation strategies [33,34,36,39,40]. Thus, given the ultrathin CIGS solar cells challenges a baseline model will help understand the technology current limitations and pave the way for future improvement strategies.…”