Perovskite solar cell developed with superpower conversion efficiency

Researchers say Solar module manufacturers should begin testing new technologies in higher-value niche markets. Only such markets can bring cutting-edge PV technologies such as perovskites to commercial maturity. Though it might seem prohibitive in mainstream market in terms of initial investment, segments like building-integrated PV or microelectronics devices can offer commercial maturity.

Perovskite solar cell with a power conversion efficiency of 25.2% have been fabricated by the researchers at the Massachusetts Institute of Technology (MIT). It is developed through the chemical bath deposition method. CBD is a technique to produce films of solid inorganic, non-metallic materials on substrates by immersing the substrate in a precursor aqueous solution. Thiourea (TU) is a compound used in thin-film solar cells to achieve high-quality films in the film-deposition process.

If the conductive layer is directly attached to the perovskite, there will be no current flow as the electrons and their counterparts, called holes, simply recombine on the spot. If the perovskite and the conductive layer are separated by this intermediate layer, the latter lets the electrons through and prevents the recombination.
The US scientists added a special conductive layer of tin dioxide bonded between the conductive layer and the perovskite material. The special conductive layer was treated with a chemical bath at 90 degrees Celsius, which made the precursor chemicals slowly decompose to form the layer of tin dioxide in place.
Having understood the decomposition mechanisms of these precursors, the researchers were able to find the right window in which the electron transport layer with ideal properties could be synthesized.

Depending on the acidity of the precursor solution different mixtures of intermediate compounds form and it produce more effective films. The perovskite layer is further improved by adding special additives that do not alter the material’s bandgap. The positive effect of this special conductive layer when combined with an improvement of the perovskite layer has resulted in the development of perovskite cells that boost efficiencies. The achieved conversion efficiency of the solar cell was thus far demonstrated in tiny lab-scale devices. Even with a single active layer, we can make efficiencies that threaten silicon.

Advantages of perovskite solar cells:

• It increases efficiency and lowers the cost of solar energy.
• It has low potential material & reduced processing costs.
• It can react to various different wavelengths of light, which lets them convert more of the sunlight that reaches them into electricity.
• It offers flexibility, semi-transparency, tailored form factors and light-weight.
• They degrade when exposed to heat and moisture.
• They are less durable than silicon ones, which have lifetimes of more than 25 years.
Perovskite solar cells offer the tantalising possibility of higher energy efficiency and faster manufacturing than regular commercial silicon panels. Researchers have scaled up perovskite cells before but they aren’t commercially viable yet.
Perovskite solar cells are the most emerging area of research among different new generation photovoltaic technologies due to its super power conversion efficiency.

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