CIGS absorber preparation by non-vacuum particle-based screen printing and RTA densification

CuIn_0.7Ga_0.3Se₂ (CIGS) thin-films are prepared by the particle-based screen printing technique followed by rapid thermal annealing (RTA) densification. Due to the short RTA time, CIGS absorber remains the ideal stoichiometric ratio originated from the CIGS particles in the coating paste and thus the conventional selenization process is not required. The effects of the particle concentrations of the coating paste, the RTA temperature and normal loading during RTA on the performances of the CIGS thin-films are studied. The film thickness increases with the increase of the particle concentration of the coating paste. The carbon content of the film is nearly zero when the RTA temperature is greater than 650°C. The carrier concentration and Hall mobility of the CIGS film increase when increasing the RTA temperature from 300°C to 650°C. Using the coating paste with a particle concentration of 40wt% for screen printing and a three-step, 250°C solvent removal for 5min, 500°C annealing for 7min and 650°C densification for 3min, 1.97Ncm^-2 normal loading RTA process, a p-type chalcopyrite CIGS film with the carrier concentration of 1.23×10¹⁵cm^-3 and mobility of 26.21cm²V^-1s^-1 is obtained.