The Perovskite-Info newsletter (February 22, 2022)

Researchers from Korea and the USA have used an imaging technique to observe structural changes at the atomic level suggesting strategies to reduce perovskite solar cell degradation.

Perovskite solar cells (PSCs) tend to degrade quickly. When they are exposed to sunlight, freely moving ion vacancies form in the structure and migrate towards the electrodes. In dark conditions, the effect is reversed, and the ions are once again redistributed in the perovskite structure. Repeated cycles of this ion transport during the operation of the solar cell permanently degrade the cell and result in short lifetimes. However, degradation at the atomic level due to ion migration has not been directly observed.

Researchers from the University of Amsterdam and NWO-Institute AMOLF have examined the efficiency gain offered by perovskite/silicon tandem solar cells containing several semiconductors with diverse energy gaps, with a spectrum splitter added between the top and bottom terminals.

This design allows the tandem solar cells to be responsive to a wider region of the sunlight's spectrum. However, such cells usually deal with ineffective light trapping and management due to parasitic light absorption in inactive layers and reflection between layers. Various studies have looked into these issues, yet the idea of spreading sunlight in the tandem subcells with controlled spectral splitting was not adequately investigated.

Researchers from King Abdullah University of Science and Technology (KAUST) and National Yang Ming Chiao Tung University have reported what they say is the first-ever successful photovoltaic (PV) damp-heat test of perovskite solar cells.

The damp-heat test is an accelerated and rigorous environmental aging test aimed at determining the ability of solar panels to withstand prolonged exposure to high humidity penetration and elevated temperatures. The test is run for 1,000 hours under a controlled environment of 85% humidity and 85 degrees Celsius. It is meant to replicate multiple years of outdoor exposure and evaluate factors such as corrosion and delamination.

It was recently reported that Chinese researchers from the ECNU and the Ningbo Institute of Materials Technology and Engineering under the Chinese Academy of Sciences were successful in developing a type of perovskite solar cell (PSC) with high power conversion efficiency.

PSCs can be generally classified into two categories, n-i-p devices and inverted p-i-n devices. The p-i-n PSCs can be produced at low temperature with good stability, and are compatible with crystal silicon cell to achieve the development of laminated cell, said Fang Junfeng, professor at the East China Normal University (ECNU). At present, the efficiency of n-i-p perovskite cells has reached 25%, while the maximum efficiency of inverted p-i-n devices remains at 22%-23%.

Researchers at the University of Rome Tor Vergata's Centre for Hybrid and Organic Solar Energy (CHOSE), collaboration with Greatcell Solar Italy, Technische Universität Dresden and Istituto di Struttura della Materia (ISM-CNR), have designed a way to reduce cell-to-module losses in perovskite solar modules, by optimizing the laser design, establishing a relationship between geometrical fill factor, cell area width, and P1–P2–P3 laser parameters.

In their new work, the research team presented a complete assessment of the optimization of the laser and design of perovskite solar modules. They also transferred these optimizations to a minipanel size, proving the durability of the process.