SEMINAR

Majority and minority carrier properties represent fundamental parameters governing semiconductor device performance. Obtaining this information simultaneously under light illumination would unlock many critical parameters such as recombination lifetime, recombination coefficient, and diffusion length; while of critical importance for optoelectronic devices and solar cells, this goal has remained elusive. Studies to collect both majority/minority carrier properties for high-performance light absorbing materials have been attempted, but require a wide range of experimental techniques, which typically use different sample configurations and illumination levels thereby presenting additional complications in the analysis. Here, we demonstrate a carrier-resolved photo Hall technique that rests on a new identity relating hole-electron Hall mobility difference, Hall coefficient and conductivity. This discovery, together with advances in ac-field Hall measurement using a rotating parallel dipole line system, allows us to unlock a host of critical parameters for both majority and minority carriers. We successfully apply this technique to various light absorbers such as Si, Cu₂ZnSn(S,Se)₄, organometal lead halide perovskites, (FA,MA)Pb(I,Br)₃ and map the results against varying light intensities, demonstrating unprecedented simultaneous access to these parameters. This information, buried in the photo-Hall measurement, has so far been elusive for 140 years since the original discovery of Hall effect. Beyond historical significance, the applications of simultaneous majority and minority carrier measurement are broad, including photovoltaics, optoelectronics and various electronic devices.