Nb ₂O ₅ as a new electron transport layer for double junction polymer solar cells

Nb ₂O ₅ as a new electron transport layer (ETL) was used for double junction polymer solar cells. The Nb ₂O ₅ ETL was prepared by spin coating a Nb ₂O ₅ sol-gel solution onto the active layer of the optical front subcell. The double junction devices using Nb ₂O ₅ ETL exhibit an open circuit voltage (V _oc) of 1.30 V, which is close to the sum of the s of the individual subcells. The current density-voltage (J-V) simulation showed that the double junction device performance using Nb ₂O ₅ as ETL could be significantly increased by reducing the series resistance (R _se) and matching the current densities of the individual subcells.