Impact of perovskite precursor solution temperature on charge carrier dynamics and photovoltaic performance of perovskite based solar cells

Abstract

Even though perovskite based solar cells have been routinely fabricated with preheated perovskite solutions, currently the underlying mechanism of how the perovskite precursor solution temperature influences perovskite solar cells has not been studied yet. Therefore, we investigated the impacts of perovskite solution temperatures on charge carrier dynamics of perovskite film and perovskite solar cell performance that were quantitatively analyzed using steady-state photoluminescence (PL), time-resolved emission spectra (TRES), excitation-dependence of PL and current-voltage measurements. It is found that the perovskite solution temperature greatly influenced the morphologies, defect densities and states, and charge recombination dynamics of perovskite thin films. Particularly, steady-state and time-resoled PL measurements revealed that perovskite thin films prepared with the perovskite solution temperature around 70 °C produced lowest surface and bulk defect densities. In addition, it is found that the perovskite solution temperature around 70 °C led to exciton-like transitions while lower and higher solution temperatures led to defect-mediated recombination of perovskite thin films. Such recombination dynamics of perovskite films strongly influenced the light absorption and extraction efficiencies of photogenerated charge carriers which in turn influenced short-circuit current, fill factor, and open circuit voltage of perovskite solar cells. As a result, better photovoltaic performance of perovskite solar cells was observed when prepared with the precursor temperature around 70 °C.