# Overview on Different Types of Solar Cells: An Update
###### Abstract
After absorption and charge transmission, the photovoltaic process requires the extraction of the photogenerated charge. As a result, the optimal extraction interface should provide the least possible voltage, current, and FF loss. An optimal selective contact should not absorb light to prevent the reduction of light intensity in the perovskite. Similarly, there should not be any energetic losses during the absorber injection (no interfacial recombination). These contact materials need to be selective to enable one kind of carrier to be injected, but they also need to lower series resistance. One of two major processes can result in charge separation in perovskite. One involves injecting photogenerated electrons into an n-type semiconductor such as TiO\({}_{2}\), while the other involves injecting holes into a p-type material that transports holes, such as spiro-OMeTAD. To stop holes from reaching the TCO substrate (anode) and short-circuiting the cell, a hole-blocking layer is utilized between the TCO-conducting substrate and the mesoscopic scaffold and/or perovskite layer. On the other hand, using a mesoporous TiO\({}_{2}\) layer greatly lessens the hysteresis behavior of PSC even if a hybrid organic-inorganic perovskite absorber can transfer photogenerated electrons to the conductive substrate itself. Dye-sensitized solar cells (DSSC) were first discovered by professor [PERSON] in 1991. The DSSC consists of a working electrode [11], a counter electrode, and an electrolyte. Dyes (natural organic materials and synthetic materials) are attached to the TiO\({}_{2}\) films, serve as the working electrodes. The DSSC consisting of ruthenium (II) polypyridyl complex (N3 dye) [12] showed a power-conversion efficiency of about 10%. A platinum conductive glass served as the counter electrode [11]. The working principle of DSSC converts sunlight into electricity through the creation of exciton. The semiconductor material is placed on a conductive transparent plate to form a thin layer. A dye monolayer layer is placed on the surface of the semiconductor. Photoexcitation experienced by the dye produces electrons excited from the valence band to the conduction band of the dye, which then enter the conduction band of the metal oxide. This electron injection is performed through the connection between titanium and the carboxyl group in the dye. This process produces a positively charged dye and a negatively charged TiO\({}_{2}\) particle. The electrons then exit through the external circuit to the opposite electrode. This flow of electrons is used as electrical energy. The electron vacancies in the valence band of the dye are replaced by electrons from the electrolyte. The electrolyte used in DSSC is usually an organic solvent containing a redox system such as an iodide-triiodide pair. The regeneration of the sensitizer by iodide occurs by donating electrons in the valence band of the oxidized dye. The iodide is regenerated by reducing the triiodide at the opposite electrode by utilizing electrons from the external circuit. This process takes place continuously as a cycle so that a continuous current is produced. Metal chalcogenide films are considered as important materials for solar-cell applications [13]. Several types of films (metal sulfide, metal selenide, and metal telluride) have been prepared using a vacuum method or non-vacuum deposition technique [14]. These films could be cheaper to produce, show good quality materials, and have the most potential for the future. In this work, the advantages and limitations of each type of solar cell (thin-film solar cells, dye-sensitized solar cells, and organic solar cells) were highlighted. Photovoltaic parameters were investigated based on the selected literature review.