This article introduces the development, structure and work mechanism of perovskite solar cells. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.

1. An Introduction of Perovskite Solar Cells
Development of perovskite solar cells
In 2009, Akihiro Kojima, a professor at Yokohama University in Japan, first prepared CH3NH3PbI3
and CH3NH3PbBr3 as light absorbing layers for dye-sensitized solar cells, achieving 3.8%
efficiency. Later, the perovskite material decomposes quickly due to the liquid electrolyte, so that
the battery efficiency is quickly attenuated. But researchers quickly realized that perovskites
absorb sunlight and carry electricity. In recent years, the development of perovskite solar cells
have been rapid. With the continuous development of the preparation process and
commercialization process, the photoelectric conversion efficiency of perovskite solar cells has
increased from 3.8% in 2009 to 20.1%. Compared with the solar cells of the silicon era, the
perovskite solar cell is expected to occupy a large share in the future solar cell industry.
Structure of perovskite solar cells
The name of the perovskite solar cell is derived from the fact that its light absorbing layer
(CH3NH3PbIx) has a perovskite structure, not because it contains calcium titanate (CaTiO3). This
type of organic-inorganic mixed metal halide-based perovskite structural semiconductor exists in
the form of the common ABX3 wherein A is a monovalent organic cation, B is a metal cation, and
X is a halogenated anion. The most commonly used organic-inorganic perovskite material is
CH3NH3PbI3-x-yBrxCly (MAPbI3-x-yBrxCly). Perovskite solar cells are ideal for photovoltaics,
semiconductor light sources, and even lasers. A highly crystalline film precursor can be prepared
by a low temperature solution method, the band gap of which can be adjusted by modifying the
halide component. Such perovskite solar cells exhibit excellent high photoluminescence lifetime
and mobility.
The main structure of the perovskite solar cell includes FTO conductive glass, dense layer,
mesoporous layer, insulating layer, and carbon counter electrode.
FTO conductive glass
The primary role of conductive glass in batteries is to collect and transport electrons. Perovskite
solar cells are generally made of fluorine-doped tin oxide conductive glass. The laser-etched FTO
can be used as a base material.
Dense layer
The dense layer of TiO2 is generally an n-type semiconductor and functions to transport
electrons. In general, the optimal thickness of the TiO2 dense layer is 50-100 nm, so as not to
affect its series resistance.
Mesoporous layer
The TiO2 mesoporous layer is a thin film layer with electron transport function and channel
function, and this layer is optional during the experiment.
Insulating layer
The ZrO2 insulation layer is printed primarily to avoid short-circuit of the battery.

2. Carbon counter electrode
Replacing the metal electrode with a carbon counter electrode not only reduces the cost, but
also effectively improves the humidity stability of the battery.
Work mechanism of perovskite solar cells
The photoelectric conversion mechanism of a perovskite solar cell is as follows: When sunlight is
irradiated onto the FTO, the perovskite light absorbing layer first absorbs photons to generate
electron-hole pairs. Since the perovskite material has different binding ability to excited
electron-hole pairs, and these perovskite materials tend to have low carrier recombination
probability and high carrier mobility, so the diffusion length and lifetime of these carriers is long.
The carrier diffusion length of methylaminoiodide (CH3NH3PbI3) reaches 100 nm, while the
diffusion of chlorine-doped methylaminoiodide (CH3NH3PbI3-xClx) is even greater than 1 μm.