A nanofibrillar conjugated polymer film as an interface layer for high-performance CsPbIBr2 solar cells with efficiency exceeding 11%†
Abstract
The perovskite/hole-transporting layer interface plays a crucial role in the performance of perovskite solar cells. Herein, a conjugated polymer (CP) is employed as an interface layer in CsPbIBr2 solar cells. On top of the CsPbIBr2 layer, the CP self-assembled into a nanofibrillar film which shows multiple effects: optimization of the energy level alignment, enhancement of the hole extraction, passivation of the perovskite layer and reduction of the defect density. As a result, the power conversion efficiency of the corresponding CsPbIBr2/CP device is improved to 11.05%, with a VOC of 1.19 V, a JSC of 12.69 mA cm−2, and a FF of 73.31%. Moreover, the device efficiency retains about 91% of its initial value for nearly 900 hours in air. This proposed CP-passivated interface strategy will open a new avenue for achieving high-performance inorganic perovskite solar cells.