TRANSPARENT CONTACT FOR PEROVSKITE BASED SOLAR CELLS

A solar cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. Light, with a sufficient energy, is absorbed by a semiconductor, causing excitation of an electron to a higher-energy state. An electric potential is produced by the separation of charges.

Organometal halide perovskite is a promising material in photovoltaic cells. Perovskite has a large absorption coefficient in the visible region, high carrier mobility and tunable band gap energy, facilitating its use as a light harvester in a solar cell. ֲ The contact between the cell and the electric circuit is made of gold, to assure good conductivity and that the holes and electrons transfer from the perovskite to the electric circuit. ֲ If some of the light is not converted to electricity, that part of the light is lost.

A tandem cell is made up of two cells one top of the other, to increase the performance of the solar cell. The composition of perovskite is different in each cell, so each cell collects a different part of the spectrum. The light enters the first cell, a part of it is converted into electricity, the other part enters the second cell and is also converted. ֲ Between the two cells, the contact must be electrically conductive and transparent to light. ֲ The gold contact must be replaced by a multilayer contact; the multilayer architecture is dielectric - metal - dielectric. When the thin gold film is sandwiched between the two dielectric layers, destructive interference in the visible range can be achieved through simple tuning of the exact layer thicknesses to provide an increase in transparency.