Setting boundaries on the recipe for a successful RbF post-deposition treatment of CIGS

Abstract

RbF post-deposition treatments have been explored in the literature for increasing the open-circuit voltage, fill factor, and hence the efficiency of Cu(In,Ga)Se 2 solar cells. However, given the few papers documenting the experimental steps, it was difficult to quickly reproduce the results. This contribution describes some of the optimization steps that led to a successful RbF PDT based on device performance. We present results that put boundaries on the temperatures of the RbF cell and the lamp (for sample heating) setpoint. The best recipe for our specific growth process is documented in detail so that others may copy the procedure and possibly arrive at a successful RbF PDT in a reasonable time. • RbF post-deposition treatment of CIGS was more difficult to optimize than KF post-deposition treatment. • The importance of RbF PDT parameters from most to least is RbF cell temperature, substrate temperature, and Se flux. • Successful RbF PDTs were achieved with RbF cell temperature from 505 °C through 555 °C with the best at 540 °C. • Lamp setpoint temperature from 400 °C through 540 °C work for RbF PDTs. • Lists detailed recipe for NREL’s best RbF post-deposition treatment.