Exceeding 100 percent quantum efficiency in the photocurrent of a hybrid inorganic-organic semiconductor

An international team has been able to achieve a quantum efficiency greater than 100 percent with the help of tiny crystals.

Light-harvesting applications and impressive performances in solar cells are some of the things perovskites can do. Improvements in photo-conversion efficiency are needed to take this technology to a larger market.

Light is made up of packets of energy. A negatively charged electron and a positively charged electron are transferred to each other when a photon is absorbed by a Semiconductor. The particles can be swept in opposite directions by an electric field. The basics of a solar cell are shown here. It might sound simple, but getting as many electron-hole pairs from the incoming photon as possible has been a goal for a long time.

Excess energy is lost as heat when the photon has more energy than is needed. There is a solution. More than one electron-hole pair can be achieved by using small particles.

Jun Yin and Omar Mohammed from KAUST worked with Yifan Chen and Mingjie Li from Hong Kong Polytechnic University and their colleagues to demonstrate a phenomenon called multiple exciton generation. Yin says that they demonstrated a photocurrent quantum efficiency greater than 100 percent.

MEG has been observed in the past in the form of a large bandgap in perovskites.

The excited electron-hole pairs are too fast for them to be removed from a solar cell device. Yin says that efficiency and verification of their inherent MEG have not been reported.

The semiconducting material made using small amounts of tin was embedded in tin-free FAPbI 3. Tin helps to slow the cooling. Yin says that they will be able to improve the light-power conversion by altering the composition of the perovskite.

The research was published in a peer reviewed journal.

More information: Yifan Chen et al, Multiple exciton generation in tin–lead halide perovskite nanocrystals for photocurrent quantum efficiency enhancement, Nature Photonics (2022). DOI: 10.1038/s41566-022-01006-x Journal information: Nature Photonics