7/18/2025 Tyler Wolpert
Bioengineering professors Shuming Nie and Viktor Gruev highlight how perovskite materials can transform digital imaging. Unlike silicon-based sensors that lose most incoming light and rely on color filters, perovskites enable each pixel to directly capture full-color data, improving brightness, resolution, and color fidelity, especially in low-light settings. The team’s recent advances include a UV imaging sensor inspired by butterfly vision, with potential applications in cancer detection and multispectral biomedical imaging.
Written by Tyler Wolpert
Camera Sensors Made from Perovskite Materials Improve Color Fidelity, Imaging Brightness and Resolution
A picture is worth a thousand words, but current cameras cannot tell the whole story. Most cameras, like those in smartphones or tablets, capture photos using silicon pixels that convert light into electric currents. However, each pixel can only detect one primary color (red, green, or blue), meaning about two-thirds of the incoming light is lost. To compensate for this loss, four pixels (one blue, one red, and two green) are combined to create one color pixel. This is fine for most applications, but for demanding low-light medical or military imaging applications, this can result in grainy (noisy) and not so colorful photos (due to loss of spectral or chromatic information). Cancer Center at Illinois researchers Shuming Nie and Viktor Gruev recently published a commentary piece on the state-of-art of digital color imaging technologies for Nature, providing insights into the latest research breakthroughs and future directions.
Developing a Better Image
Photographers have long sought to create brighter, richer images. Early digital cameras used silicon pixels that converted light into electric currents. However, silicon pixels themselves are not sensitive to colors, so cameras had to rely on mosaic color filters to selectively pass the three primary colors (red, green, and blue), and signals from at least three pixels are then recombined to creative a color pixel. This is now the dominant technology for essentially all digital cameras and optoelectronic color imagers.
However, this approach has two problems. The first is that the colors are not true colors, because they are “synthesized” from multiple pixels. The second problem is that this approach discards two-thirds of the available light, which is certainly not desirable when the number of available photos is limited.
Ironically, the next generation of digital cameras drew inspiration from what some would consider an outdated technology: Kodachrome films, a color film introduced in 1935, consisted of three emulsion layers capable of capturing the full color spectrum.
In 2002, engineers used this approach as an alternative to filters by building a silicon sensor consisting of three light-sensing layers stacked on top of one another. This vertical stack delivered the first filter-free color images. However, this approach causes an overlap of captured light, resulting in distorted colors and limited image resolution.
Today, researchers are exploring the use of perovskite crystals, a mineral with the same crystalline structure as calcium titanium oxide. Both macroscopic and nanoscale perovskite crystals can be produced in large quantities, exhibiting fascinating optoelectronic properties such as quantum confinement and highly efficient light emission. Like silicon, perovskites generate an electrical current when they absorb light, but they do so much more efficiently. Unlike silicon, each perovskite crystal can absorb a narrow band of red, green, or blue light. That is, perovskite devices are able to simultaneously achieve color selection and photoelectric generation in one shot, leading to more light capture and higher quality images with less processing relative to traditional silicon cameras.
“By stacking multiple perovskite layers, each tuned to a different band, one can use a single pixel to capture the full color spectrum without any external filters,” said Dr Nie. “In essence, spectral selection is accomplished within the device structure itself, rather than by a separate overlay filter,” he continues.
The Bigger Picture
Considerable development needs to happen before perovskite crystals become a commonplace technology. Among other issues, researchers can only create small pixel arrays that measure only a few millimeters across. Additionally, perovskites become unstable when they react with moisture and oxygen, and their lead content raises environmental concerns.
To address these issues, chemists must improve the stability of perovskites and search for lead-free alternatives. Physicists must fine-tune the thickness of the layers and engineer the interfaces between the parts of the device to maximize both the absorption of photons and the charge transferred to the external electronics. The fabrication must also be scaled up to produce centimeter-scale wafers for commercial and scientific use.
However, the benefits of undertaking this work are clear. Capturing more light and better images would drastically improve scientific fields like biomedical imaging or astronomy. Perovskite materials could facilitate the development of tiny, multispectral cameras to detect cancer, monitor environmental changes, or screen for counterfeit currency. And yes, selfies or holiday photos will pop and impress.
New Horizons
Illinois researchers are also actively pursuing a new direction in integrating perovskite nanocrystals and CMOS chips for cutting-edge biomedical imaging. In particular, Gruev, Nie and their coworkers have developed a bioinspired UV imaging sensor for wavelength resolved imaging in the UV spectrum (Bioinspired, vertically stacked, and perovskite nanocrystal–enhanced CMOS imaging sensors for resolving UV spectral signatures, ScienceAdvances, 2023). Inspired by the Papilio butterfly’s ability to distinguish ultraviolet hues using layered eyes, the authors coated a conventional sensor with a layer of fluorescent perovskite nanocrystals. Part of the incoming UV light is absorbed by this nanocrystal layer and re-emitted as visible light (which the underlying silicon pixels detect), while the remaining UV portion passes through and is detected by a top-layer UV-sensitive photodiode. By comparing the two signals, the system achieves wavelength-resolved UV imaging – effectively a dual-band UV sensor in each pixel. This allowed label-free detection of biological substances via their UV autofluorescence, enabling, for instance, real-time differentiation of cancerous vs normal cells with 99% confidence in tests.
As to the future, Dr Nie says “Perovskite crystals are also excellent materials for down/up photon conversation and scintillation, which could be integrated with CMOS photodiode arrays for multispectral imaging beyond the visible spectrum, spanning from infrared wavelengths to ultraviolet, and even to high-energy x-rays and gamma-rays.”
The original commentary, “Light detectors made from perovskite crystals see in full colour,” was published on June 18, 2025, and can be found at www.nature.com/articles/d41586-025-01705-9.
Viktor Gruev is the Dunning Endowed Faculty Scholar in the Department of Electrical and Computer Engineering. He has affiliations in the Departments of Bioengineering and Biomedical and Translational Sciences and the Beckman Institute for Advanced Science and Technology. He also co-leads the Cancer Center at Illinois’s Cancer Technology and Data Science research program.
Shuming Nie is the W. W. Grainger Chair in Bioengineering. He has affiliations in the Micro and Nanotechnology Lab, and the Departments of Electrical and Computer Engineering, Materials Science and Engineering, and Chemistry.