What is a Charge Carrier Lifetime in a Perovskite Solar Cell?
Lifetimes of charge carriers are a key metric to quantify recombination in solar cells. However, due to different measurement modes, the word “lifetime” might mean many different things thereby making quantitative comparisons impossible. Here a consistent model for transient spectroscopy analysis is shown to solve this problem.
Recombination of charge carriers in solar cells is often analyzed using transient optical spectroscopy. Usually, the response of a sample to a laser pulse is studied and from the decay, conclusions about the severity of recombination are made. The downside of this approach is that it is unable to distinguish between a variety of different transient phenomena that occur in solar cells. To distinguish the mechanisms, a sensible model is required. Here, Krückemeier et al propose a relatively simple analytical model that allows to extract information from a variety of different methods such as transient photoluminescence (laser pulse in – luminescence transient out) and transient photovoltage (laser pulse in – voltage transient out). In particular, the model allows distinguishing different recombination mechanisms from each other as well as disentangling capacitive effects due to electrode charging and discharging from recombination.
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