Advantages and Problems of Perovskite Solar Cell

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Advantages and Problems of Perovskite Solar Cell
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1 Introduction

• As global energy consumption continues to grow
  and environmental pollution becomes more serious,
  replacing traditional energy sources with clean
  renewable energy is imminent. Solar energy is
  widely used due to its widespread distribution.
  Solar cells are the most important way to use
  solar energy, and new types of solar cells with
  perovskite as light absorbing materials are
  developing rapidly. The perovskite material can
  be used not only as a light absorbing layer but
  also as an electron transport layer (ETM) and a
  hole transport layer (HTM). Due to the high light
  absorption coefficient, lower cost and simple
  preparation of the perovskite solar cell, it has
  attracted widespread attention.

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2 Work Mechanism of Perovskite Solar Cell

• Under illumination, photons with energy greater
  than the forbidden band width of the light
  absorbing layer will be absorbed by the material
  in the light absorbing layer, while valence
  electrons in the layer are excited into the
  conduction band and leave holes in the valence
  band. When the conduction band energy level of
  the light absorbing layer is higher than the
  conduction band energy level of the electron
  transport layer, the conduction band electrons in
  the light absorbing layer are injected into the
  conduction band of the electron transport layer,
  and the electrons are further transported to the
  anode and the external circuit. And when the
  valence band energy level of the light absorbing
  layer is lower than the valence band energy level
  of the hole transport layer, holes in the light
  absorbing layer are injected into the hole
  transport layer, and holes are transported to the
  cathode and the external circuit to form a
  complete loop. The main function of the dense
  layer is to collect electrons injected from the
  perovskite absorption layer, thereby causing
  charge separation of the electron-hole pairs of
  the perovskite absorption layer. In addition, the
  dense layer also acts as a barrier to prevent the
  contact of the perovskite with the FTO to avoid
  the recombination of electrons with the FTO.

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3 Advantages of Perovskite Solar Cell

• Compared with existing solar cell technologies,
  perovskite materials and devices have the
  following advantages

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3.1 Excellent comprehensive performance

• This new inorganic/organic composite perovskite
  material has excellent comprehensive performance
  it can efficiently perform the absorption of
  incident light, the excitation, transport and
  separation of photogenerated carriers at the same
  time.

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3.2 High extinction coefficient and appropriate
band gap width

• The perovskite material has a good energy band
  width of about 1.5 eV, and has a very high
  extinction coefficient, and the light absorption
  capacity is more than 10 times higher than other
  organic dyes. In terms of optoelectronic
  properties, the methylamine lead halide
  perovskite material exhibits excellent
  performance, and its light absorption ability is
  more than 10 times higher than that of the dye,
  and is an ideal material for developing
  high-efficiency and low-cost solar cells.

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3.3 Excellent bipolar carrier transport properties

• Such perovskite materials are capable of
  efficiently transporting electrons and holes. The
  electron/hole transport length is greater than 1
  µm, and the carrier lifetime is much longer than
  other solar cells.

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3.4 Higher open circuit voltage

• The biggest advantage of a perovskite battery is
  that it produces a high open circuit voltage
  under full illumination. The current open circuit
  voltage of perovskite solar cells has reached
  1.3V, which is close to that of GaAs cells and
  much higher than other batteries, indicating that
  its energy loss under full sunlight is very low,
  and the conversion efficiency has a large room
  for improvement.

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3.5 Simple structure

• The battery is composed of a transparent
  electrode, an electron transport layer, a
  perovskite light absorbing layer, a hole
  transport layer, and a metal electrode, and can
  be made into a P-I-N type planar structure, which
  is advantageous for scale production.

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3.6 Mild preparation conditions

• The core material of the battery - the composite
  perovskite material can be prepared by mild
  preparation methods such as coating, vapor
  deposition, and mixing processes, which are
  simple in process, low in manufacturing cost and
  energy consumption.

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4 Problems of Perovskite Solar Cell

• At present, the photoelectric conversion
  efficiency of perovskite solar cells has exceeded
  20 at the laboratory level, but there are still
  several key factors that limit the development of
  perovskite solar cells.

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4.1 Poor reproducibility of high performance
battery

• Perovskite solar cells are very sensitive to
  changes in conditions during the preparation
  process, which results in a large statistical
  bias in the photoelectric conversion efficiency
  of a group of cells prepared under the same
  conditions. Although the conversion efficiency of
  perovskite solar cells has been increasing, poor
  reproducibility will affect large-scale
  applications and further scientific research in
  the future.

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4.2 Stability of solar cell

• Exposure to the atmosphere makes the
  photoelectric conversion efficiency of perovskite
  solar cells severely attenuated. In addition,
  ultraviolet light, temperature, moisture, and
  organic molecules also affect the stability of
  the perovskite solar cell.

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4.3 Preparation of large area solar cells

• The effective illumination area of the perovskite
  solar cell with high conversion efficiency is
  relatively small, and the uniformity of the
  device film is deteriorated after the preparation
  area is increased, so that the conversion
  efficiency of the large-area solar cell is low.
  At present, the most common method for preparing
  perovskite solar cells is spin coating, which is
  not conducive to the preparation of large-area,
  continuous perovskite films.

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4.4 Environmental pollution problems

• The absorption layer of the commonly used
  perovskite solar cell contains soluble heavy
  metal Pb. Also, toxic organic solvents may be
  used during device preparation, which may cause
  environmental pollution. The development of
  environmentally friendly Pb-free perovskite solar
  cells has become a new research direction.

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5 Conclusion

• Due to the unique properties of perovskite solar
  cells, they have a very bright industrial
  prospect and have become one of the most
  promising competitors of existing commercial
  solar cells. Therefore, the research of
  perovskite solar cells is of great significance
  to seize the opportunities of the development of
  solar cell industry and promote the upgrading of
  new solar cell technology. In the long run,
  promoting the large-scale industrialization of
  perovskite solar cells will enable mankind to
  obtain cheaper and more convenient
  environmentally friendly clean energy, and even
  have important significance for the sustainable
  development of the entire human race.