Additive-Assisted Interfacial Engineering for Efficient Carbon-Based Perovskite Solar Cell Incorporated Dopant-Free Polymeric Hole Conductor PBDT(S)-T1

With the advantage of low-cost, simple processability and high stability, carbon-based perovskite solar cells (C-PSCs) show great potential for large-scaled production. However, the photovoltaic performance of C-PSCs is restricted due to the poor hole selectivity of carbon electrode and high trap density at the interface between perovskite and carbon electrode. Herein, dopant-free π-conjugated polymer PBDT(S)-T1 processed with additive 1,8-diiodooctane (DIO) was applied to improve anode-side interface within C-PSCs devices. A suitable energy level of PBDT(S)-T1 enables efficient hole extraction and collection at the carbon electrode. Besides, the incorporation of DIO could simultaneously increase the crystallinity of PBDT(S)-T1 and enhance the connection between perovskite as well as polymeric hole conductor, facilitating efficient charge transfer and defect passivation. C-PSCs with PBDT(S)-T1/DIO realize the highest efficiency of 14.82%, which is 20% higher than that of the control device without interface modification (12.25%). This study provides an efficient strategy to enhance the device performance of C-PSCs through the incorporation of dopant-free π-conjugated polymer and DIO-assisted interface engineering.