Paper by Karl Leo on photon recycling published in the journal Science Advances

Metal halide perovskites are receiv­ing great atten­tion as next-gener­a­tion semicon­duc­tors for solar energy conver­sion. Since the first demon­stra­tion of 3.8% efficiency in 2009, efficien­cies have increased rapidly and state-of-the-art perovskite solar cells exhibit high efficien­cies of over 25%.

To further increase the efficien­cies of perovskite solar cells, the solar cell must not only be a good light absorber, but also a good light emitter. The researchers from the Dresden Integrated Center for Applied Physics and Photonic Materi­als (IAPP) at the TU Dresden noted the role of the photon recycling effect. When a photon is radiated inside re-absorb­ing semicon­duc­tors such as perovskites, it can be re-absorbed by the emitter itself and gener­ate a new photon via photo­lu­mi­nes­cence. Such a process of recur­sively re-absorb­ing and re-emitting the photons is called photon recycling.

The IAPP team demon­strated that photon recycling and light scatter­ing effects greatly improve the light emission efficiency by a factor of about five, signif­i­cantly improv­ing the photo voltage of perovskite solar cells. It was shown, that the upper limit for the efficiency of the perovskite solar cells increases from 29.2% to 31.3% with the help of photon recycling.

“Our research shows the poten­tials of the technol­ogy, but much further effort in research and devel­op­ment is needed before the technol­ogy can enter mass produc­tion”, says Hector Fellow Karl Leo.

Congrat­u­la­tions to Karl Leo!