I do not know what exactly you have in mind. But if the thickness is lambda/4, that means that the reflected light will suffer destructive interference, so this will reduce the reflectance, i.e. increase the absorbed light.

Dear Neetika Yadav ,

Vesselin Donchev is right.

lambda/4 principle is used to reduce the amount of reflected light.

But with respect to solar cells I have only seen that people are using special layers in front of the active solar panel, but not, for example, the perovskite layer itself as lambda/4 layer. There is a need to protect the perovskite against the outer world; so protective means have to be used in front of the perovskite and these means will have some reflectance according to their refractive indices. Thus a separate lambda/4 layer is used just on top of the solar cell...

Best regards

G.M.

Imaging you have two bordering media with wave impedance 1 and 2. So there will be reflection. How to cancel the reflection? Put intermediate layer having quater wavelength thikness and wave impedance being geometric mean of bordering media ( being square_root( Impedance1 * Impedance2 )

E.g you see similar effect in transmission lines: https://en.wikipedia.org/wiki/Quarter-wave_impedance_transformer

Simply put : reflection on the second border travels back altogether 2*lambda /4, so 180 deg and cancels the first reflection, when amplitude is same. And it is same when impedance ratio is same on both borders

The quarter-wavelength principle optimizes perovskite solar cell thickness by maximizing light absorption and minimizing reflection. By making the perovskite layer a quarter of the wavelength of incident light, destructive interference reduces reflection, enhancing absorption. The optimal thickness is calculated using d = lamda/4n, where lambda is the target wavelength and n is the perovskite refractive index.

For E.g,, if lambda = 600 nm and n = 2.5, the optimal thickness is 60 nm. This principle helps in the design of perovskite layers and anti-reflective coatings, improving solar cell efficiency through better light management.

Dear Ayush Tara ,

thanks for your reply.

But, are you really sure about your numbers and the consequence with repect to the absorption efficiency?

The perovskite as lambda/4 plate may work, but its thickness will be around 60nm, as you pointed out. But that small thickness is very inefficient compared to the thicknesses used in perovskite solar cells, which to my knowledge is around some 100nm. One will pick up only a very small fraction of the available optical power.

One may use an odd number of lamda/4 ( d ~ (2N+1)*lambda/4*n; N being 0, 1, 2, 3...) distances for the thickness d, but then, to my opinion, you will have only a very narrow lambda space available for the efficient anti-reflection measure.

Up to now I have not seen such lambda/4 approach for the perovskite layer itself.

Maybe someone will share an example of such a system...

Best regards

G.M.