Determination of Charge-Carrier Mobility and Built-In Potential in Thin-Film Organic M-I-M Diodes from Extraction-Current Transients

We have extended the Charge Extraction by a Linearly Increasing Voltage (CELIV) technique for

determination of the built-in potential and the charge-carrier mobility in thin-film metal-insulator-metal

(M-I-M) diodes. The validity of the presented analytical theory is verified by drift-diffusion simulations

and experimentally demonstrated on organic solar cells. In contrast to the original CELIV theory, which

assumes a uniform charge-carrier distribution in the active layer of the device, here we derive an analytical

expression for determining the built-in potential and mobility in the case of a nonuniform charge-carrier

distribution where charges have diffused into the active layer from the contacts. The extended CELIV theory

is applicable on all thin-film M-I-M diodes, e.g., organic solar cells. Drift-diffusion simulations show

that the error for mobility estimation can be an order of magnitude if not correcting for the carrier profile.