Swiss researchers from Empa and ETH Zürich have created the first thin-film perovskite sensors in which red, green, and blue layers are “stacked” on top of each other. This cascaded architecture absorbs the entire photon flux of each pixel and theoretically provides three times greater light sensitivity and spatial resolution than conventional silicon matrices with color filters.
How is perovskite superior to “classic” sensors such as Hubble and James Webb?
Losses on filters. Hubble’s CCD cameras (WFC3/UVIS) have a peak quantum efficiency of up to ~85% in the yellow-green range, but due to RGB filters, each pixel receives only one-third of the available light. There are no filters in the perovskite matrix, so the actual efficiency can exceed 90% over the entire visible range.
One matrix instead of two. The HgCdTe detectors on James Webb’s NIRCam cover 0.6–5 µm with 70–90% QE, but require a two-channel scheme (short- and long-wave focuses) and cryogenic cooling to ≈37 K. Perovskite allows for “fine chemistry” to adjust the boundary zone and obtain the same spectrum in room or moderately cooled conditions, saving system mass and energy.
Hyperspectrum without filter wheel. The precise change in composition (Cl/Br/I) provides “built-in” channels for specific astrophysical lines (H-α, O III, etc.), making a mechanical wheel with filters unnecessary.
What else is missing?
To meet the requirements for spacecraft, new sensors have to go through a miniaturization phase. The pixel size in prototypes is 0.5–1 mm; for space cameras, ≤10–18 µm is required. The Empa team recognizes that this is a separate cycle of research and development work.
Radiation protection is an integral part of any structure that goes into space. Single-crystal MAPbBr₃ detectors can withstand 3 MeV protons up to a dose of 1 MGy with complete self-recovery of current at room temperature. However, a telescope in low orbit accumulates an even greater total dose over 10–15 years, so longer tests and shielding are required.
The durability of the structure and its ability to withstand degradation from UV rays and thermal cycles will also be an interesting challenge for engineers. Although vacuum protects against moisture, it is necessary to develop reliable encapsulation and “self-healing” layers to prevent the crystals from disintegrating under the influence of solar ultraviolet radiation.
Perovskite sensor technology could become useful in the coming years: its highly sensitive matrices, which do not require cumbersome cooling, enable the creation of CubeSat observatories for the rapid detection of supernova flares and gamma-ray bursts; multilayer pixels will be able to replace a whole set of mechanical filters in hyperspectral satellites for observing Earth and Mars; in lunar or asteroid landers, where every gram and watt is critically important, such sensors will provide the necessary scientific data for 2–3 years of operation; and finally, proven radiation resistance at a level of more than 100 krad will pave the way for the use of perovskite matrices in Hubble-Next and other large survey telescopes of the 2030s.
Would you like to see how the “eyes” of new telescopes could change our understanding of the Universe in the near future? Read the article “Vera Rubin Observatory: the widest view of the world around us.”
