EPFL Researchers, in collaboration with Michael Grätzel and Solaronix, have designed a low-cost and ultra-stable perovskite solar cell that has been operating at 11.2% efficiency for over a year, without loss in performance. This may represent a step towards solving the stability problem that currently poses a major obstacle towards commercialization of perovskite-based solar cell technology.

The team engineered what is known as a 2D/3D hybrid perovskite solar cell. This combines the enhanced stability of 2D perovskites with 3D forms, which efficiently absorb light across the entire visible spectrum and transport electrical charges. In this way, the scientists were able to fabricate efficient and ultra-stable solar cells, which is a crucial step for upscaling to a commercial level. The 2D/3D perovskite yields efficiencies of 12.9% (carbon-based architecture), and 14.6% (standard mesoporous solar cells).

A team of researchers at the Nanyang Technological University (NTU) has demonstrated a prototype of a flexible 30cm by 30cm plastic sheet with perovskite printed on it. To achieve this, various liquid chemicals, including the perovskite, are mixed together. The solution is then poured into a standard screen printer and printed onto sheets of plastic or glass.

The team stated that since perovskite is translucent, and its color can also be adjusted through chemical processes, perovskite solar panels could even be integrated into building facades, which is not possible with current silicon-made solar panels that are opaque and would block out light. These perovskite panels could also be cheaper to produce, costing about three times less than conventional silicon cells, the researchers said.

A multidisciplinary team at Berkeley Lab, both from the Molecular Foundry and the Joint Center for Artificial Photosynthesis, found a possible way to dramatically boost the efficiency of methylammonium lead iodide perovskite solar cells. The team discovered a surprising characteristic of a perovskite solar cell that could be exploited for higher efficiencies, possibly up to 31%.

Using photoconductive atomic force microscopy with nanometer-scale resolution, the scientists mapped two properties on the active layer of the solar cell that relate to its photovoltaic efficiency. The maps revealed a bumpy surface composed of grains about 200 nanometers in length. Each grain has multi-angled facets. Unexpectedly, the scientists discovered a big difference in energy conversion efficiency between facets on individual grains. They found poorly performing facets adjacent to highly efficient facets, with some facets approaching the material’s theoretical energy conversion limit. The scientists say these top-performing facets could hold the secret to highly efficient solar cells if the material can be synthesized so that only very efficient facets develop.