High Speed Characterization of Photovoltaic Devices

Two high speed techniques are described for characterizing minority carrier transport coefficients in photovoltaic devices. These techniques are photoluminescence lifetime and diffusion time of flight (TOF). Current theories of bulk recombination processes are reviewed. The time-dependent continuity equation is solved for diffusion in an n-p homojunction. Experimental TOF data are compared with theory to obtain the transport coefficients of minority carrier lifetime, diffusivity and diffusion length. An analytical solution is developed for the quenching of photoluminescence lifetime by current collection in the junction. This solution is compared with experimental data.