February 2022

Researchers from Germany's Helmholtz-Zentrum Berlin (HZB) and Institute for Solar Energy Research (ISFH) have reported that passivated emitter and rear cell (PERC) tech can be suitable as a basis for tandem cells with perovskite top cells.

PERC cells are usually used in mass production of silicon solar cells, and while the efficiency of the study's tandem cells is still below that of optimized PERC cells alone, the team estimates that it could be increased to up to 29.5% through targeted optimization.

KAUST researchers have developed an artificial electronic retina based on perovskite materials, that can "see" in a similar way to the human vision system and can recognize handwritten digits.

The team designed and fabricated an array of photoreceptors that detect the intensity of visible light via a change in electrical capacitance, mimicking the behavior of the eye's rod retina cells. When the array was connected to an electronic CMOS-sensing circuit and a spiking neural network (a single-layer network with 100 output neurons), it was able to recognize handwritten numbers with an accuracy of around 70%.

Last month, a group of Dartmouth College scientists developed what it refers to as 'the quickest reliable printing method for the manufacturing of perovskite solar cells'. The Dartmouth Engineering Lab's new method accelerates total processing time of solar charge transport layers (CTLs) by 60 times while maintaining reliability.

"Our method prints the layers of the solar cell with the speed and efficiency of a commercial newspaper printing press. This high manufacturing speed is important because it directly translates to lower cost per kWh, which will ultimately make solar energy more affordable for a larger population", said Dartmouth Engineering Professor William Scheideler

Researchers from the Wuhan Institute of Technology and Wuhan University have investigated key factors for realizing high-performance narrow-bandgap Pb-Sn perovskite solar cells (PSCs) via numerical simulations.

The team studied both extrinsic and intrinsic factors of efficient narrow-bandgap Pb-Sn perovskite solar cells. The effects of extrinsic factors on device performance predicted that a p-i-n structure along with appropriate charge transport layers is superior to an n-i-p structure, benefiting from a better energy band alignment. The key intrinsic factors that were studied demonstrated that surface defect density, body defect density, and film thickness of perovskite absorbers play a pivotal role in determining device performance.

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.

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 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.

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 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.

Scientists at the Karlsruhe Institute of Technology (KIT) and SUNOVATION Produktion have investigated the loss of efficiency caused by coloring the glass substrate, as part of their research on perovskite cells printed on glass.

PSCs and modules colored with inkjet-printed pigments in various bright colors and color patterns. Image from RRL Solar

The color was applied by inkjet printing, with first a white layer and then another color layer being deposited on top. The method is not new and has been used for years (by module manufacturer Sunovation Produktion GmbH of Elsenfeld, Germany, that was part of this research, and also by others) for colored modules with silicon cells. However, silicon cells absorb light in a different wavelength range than perovskite cells, which is why the same color application results in different final efficiencies.