A study of electromagnetic light propagation in a perovskite-based solar cell via a computational modelling approach

Recently, there has been huge surge of scientific interest in organic–inorganic hybrid perovskite solar cells by virtue of their high efficiency and low cost fabrication procedures. Herein, we examine the light propagation inside a planar perovskite solar cell structure ($$\hbox {ITO}/\hbox {TiO}₂/\hbox {ZnO}/\hbox {CH}₃\hbox {NH}₃\hbox {PbI}₃/\hbox {Spiro-OMeTAD/Al}$$) by solving the Helmholtz equation in the finite element-frequency domain. The simulations were conducted using the COMSOL multiphysics finite element solver to carry out the two-dimensional optical modelling of simulated solar cells in the visible region. It has been observed that shorter wavelengths of light are significantly absorbed by the top region of the photoactive perovskite layer. Specifically, at a wavelength of 400 nm, the effective optical power penetration decays to zero at only 40% of the overall length of the photoactive layer. This observation has been attributed to the high absorption coefficient of the $$\hbox {CH}₃\hbox {NH}₃\hbox {PbI}₃$$ perovskite material at shorter wavelengths. However, at longer wavelengths, the incident light propagates deeper into the photoactive layer, reaching 100% penetration. Based on the numerical computation, a maximum generation rate of $${\sim }3.43\times 10²³\,\hbox {m}³ \hbox {s}^-1$$ has been observed in the photoactive layer at a wavelength of 550 nm.