In a published article we investigated the reproducibility of charge-carrier mobility measurements in semiconducting polymer devices, particularly with respect to industrial material screening applications. In a small interlaboratory study using the space-charge limited current method, it was found that measurements of mobility on the same material could often vary by more than an order of magnitude. Unsurprisingly, it was found that using poor charge injecting electrodes led to larger variations in extracted mobility values, as well as values that clearly underestimated the mobility. More surprisingly, however, we found that there were large variations in measured mobility when identical data were analysed by different scientists. Fortunately, the variations can be reduced by following a defined protocol for data analysis and reporting.
The protocol can be downloaded below, together with a spreadsheet that accelerates the analysis and reporting. As mobility is a function of many parameters, and is strongly affected by the measurement method, we refer to values extracted using this method as mobility benchmarks - values that are indicative of charge-carrier transport under specified conditions and that may be used for materials screening comparisons.
This protocol is designed as a starting point, and we encourage the community to try it, and contribute to future improvements. If there is demand, we will use this site to produce community-developed updates to the protocol.
After trying the protocol, please provide feedback below.