Getting more out of light

04 August, 2022

Tiny crystals, known as quantum dots, have enabled an international team to achieve a quantum efficiency exceeding 100 percent in the photocurrent generated in a hybrid inorganic-organic semiconductor.


Perovskites are exciting semiconductors for light-harvesting applications and have already shown some impressive performances in solar cells. But improvements in photo-conversion efficiency are necessary to take this technology to a broader market.

Light comes in packets of energy known as photons. When a semiconductor absorbs a photon, the electromagnetic energy is transferred to a negatively charged electron and its positively charged counterpart, known as a hole. An electric field can sweep these particles in opposite directions, thereby allowing a current to flow. This is the basic operation of a solar cell. It might sound simple, but optimizing the quantum efficiency, or getting as many electron-hole pairs from the incoming photons as possible, has been a long-standing goal.


One cause of  inefficiency is that if the photon has more energy than is needed to create the electron-hole pair, the excess energy is usually lost as heat. But nanomaterials offer a solution. Small particles, such as nanocrystals or quantum dots, can convert high-energy photons into more than one electron-hole pair.


Jun Yin and Omar Mohammed from KAUST worked with Yifan Chen and Mingjie Li from Hong Kong Polytechnic University and their colleagues to demonstrate this so-called multiple exciton generation (MEG) in nanocrystals of tin-lead halide perovskite. “We demonstrated a photocurrent quantum efficiency exceeding 100 percent by harnessing MEG in the perovskite nanocrystal devices,” says Yin.


Read the full KAUST DISCOVERY story here:



  1. Chen, Y., Yin, J., Wei, Q., Wang, C., Wang, X., Ren, H., Yu, S.F., Bakr, O.M., Mohammed, O.F. & Li, M. Multiple exciton generation in tin-lead halide perovskite nanocrystals for photocurrent quantum efficiency enhancement. Nature Photonics 16, 485–490 (2022).| article