Perovskite solar cell technology has attracted widespread attention in the photovoltaic industry in recent years, showing huge development potential with its rapidly improving photoelectric conversion efficiency and significant technical advantages. From the initial 3.8% to the current conversion efficiency of 26.1%, perovskite cells have proven themselves to be the leader in third-generation photovoltaic cell technology. Perovskite cells bring higher photon utilization and the possibility of easy stacking. The precise measurements performed by UVN2800 spectrophotometer provide key data for the research and development of perovskite materials, supporting material innovation and cell performance optimization. This article will explore the key technical advantages of perovskite solar cells and their future application prospects in the photovoltaic field with the help of advanced measurement technology.

Advantage 1: Adjustable band gap brings higher theoretical conversion efficiency

Structural diagram of perovskite cell

 Perovskite materials have adjustable band gaps and high theoretical efficiency. Perovskite is a synthetic material. According to different material ratios, the band gap can be adjusted, and it can be made into a stacked battery with crystalline silicon. The band gap is the lowest energy that a semiconductor can absorb. Semiconductors cannot absorb photons with energy less than the band gap, and the energy that can be obtained from photons will not exceed the band gap energy.

The perovskite material has an adjustable band gap. When laminated with crystalline silicon materials or artificially adjusted perovskite materials, it can cover a wide range of band gaps and therefore be able to absorb light of different wavelengths. The current theoretical efficiency of single-junction perovskite cells is 31%, and the theoretical efficiency of stacking with crystalline silicon exceeds 43%.

Advantage 2: Easy to obtain raw materials, simple procedures, and reduced costs

Compared with crystalline silicon cells, the perovskite process is greatly shortened and the investment per GW of production capacity is lower. At the same time, it also eliminates the steps of silicon material purification and silicon wafer cutting at the front end of crystalline silicon cells, and the overall production cost can be significantly reduced compared to crystalline silicon cells. According to data, the preparation of crystalline silicon cells requires at least 4 processes from silicon material to photovoltaic modules. The unit process takes more than 3 days, and also requires a lot of manpower, transportation costs, etc.; while perovskite modules are produced in a single factory. The raw materials are processed directly into modules, without the traditional "cell" process, which greatly shortens the process time.

Materials for perovskite cell

The materials required for perovskite cells include packaging materials and electrode materials, among which TCO glass is the core packaging material. From the perspective of cost structure, electrode materials accounted for 37%, followed by glass and other packaging materials accounting for 32%.

Perovskite cost structure

At present, the perovskite material system has not yet been finalized, and there are many options for different film layers. Among packaging materials, TCO conductive glass commonly used in the industry is divided into three categories: ITO, FTO and AZO glass. The conductive performance of FTO is slightly inferior to that of ITO, but it has the advantages of low cost, hard film layer and suitable optical properties. At present, It is a mainstream product used in the field of photovoltaic glass. The photoelectric performance of AZO is similar to that of ITO, and the raw materials of AZO are simple and easy to obtain, and the production cost is low. It has great potential in the future industrialization process.

Perovskite crystalline silicon tandem cells

Perovskite crystalline silicon tandem cell structure

Pure perovskite cell structure: Currently, perovskite cells are divided into two categories: single-junction perovskite and tandem perovskite. Pure perovskite cells can be divided into two device structures: n-i-p and p-i-n. The n-i-p structure refers to the device structure of the electron transport layer-perovskite layer-hole transport layer, and the p-i-n structure refers to the hole transport layer-perovskite layer- The device structure of the electron transport layer, among which the n-i-p device structure is more common.

Tandem perovskite cell structure: The continuously adjustable band gap width makes perovskite suitable for tandem multi-junction cells. The advantage is that other types of solar cells can capture and convert sunlight in a wider spectrum range and improve conversion efficiency after integration. The technical direction of tandem is mainly divided into two categories, perovskite/crystalline silicon tandem cell and perovskite/perovskite tandem.

Comparison of TOPCon perovskite tandem and HJT perovskite tandem:

Perovskite and TOPCon crystalline silicon cell tandem

Perovskite and HJT crystalline silicon cell tandem

 Compared with TOPCon cells, heterojunction cells and perovskite cell tandem are more ideal. First, the heterojunction cell structure is more suitable for tandem than TOPCon cells themselves: because perovskite cells and heterojunction cells are tandem, the surface of the heterojunction cell itself is TCO, and the production line of the heterojunction cell does not need to be changed.

When TOPCon cells are tandem with perovskite cells, the silicon nitride and aluminum oxide on the front of TOPCon are insulators and cannot conduct electricity. Therefore, the aluminum oxide and silicon nitride need to be removed first, or further doping and passivation processes are added;

Second, if TOPCon cells are stacked with perovskite cells, their efficiency advantage based on high current will be wasted: from the actual mass production efficiency, TOPCon and heterojunctions are not much different, but the composition parameters of efficiency are different. Junction cells have high voltage and low current. TOPCon cells have low opening voltage but relatively high current. The main reason is that the light transmittance of TCO on the heterojunction surface is not as good as the silicon nitride on the TOPCon surface.

Third, the perovskite/HJT stacked cells have a series structure and can output ultra-high voltage to improve conversion efficiency. Perovskites and heterojunctions have good tandem cell matching and can form tandem cells with higher efficiency than single-junction PSCs.

Heterojunction refers to the space charge region (PN junction) formed at the interface by manufacturing P-type semiconductor and N-type semiconductor on the same silicon substrate, which has unidirectional conductivity. Silicon heterojunction cells with intrinsic amorphous layers contain both crystalline and amorphous silicon. Amorphous silicon can better achieve passivation effects and improve open circuit voltage and conversion efficiency.

Spectrophotometer

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The UVN2800 spectrophotometer is a detection instrument used to measure the transmittance, reflectance and absorbance of materials. The unique dual-beam optical design can perfectly correct the absorbance changes of different ITO films, allowing for stable sample measurement.

● Adopt dual light source and dual detector design

●Super large wavelength range 190-2800nm

●Double grating optical structure effectively reduces stray light

● Integrating sphere diameter can reach 100mm

●No yellowing after long-term use, stable optical properties

●Can minimize errors caused by switching detector

The continued progress and cost advantages of perovskite solar cell technology herald its broad application prospects in the photovoltaic field. With the support of high-precision measurement equipment such as the UVN2800 spectrophotometer, the research and development and performance optimization of perovskite materials will be more accurate, helping the further commercialization of the technology. Looking to the future, perovskite solar cells are expected to provide key technical support for the transformation of the global energy structure and promote the realization of sustainable development goals.