Self-charging flexible solar capacitors based on integrated perovskite solar cells and quasi-solid-state supercapacitors fabricated at low temperature

Self-charging perovskite solar capacitors (SPSCs) that harvest and store solar energy simultaneously can offer sustainable, off-grid power supply for electrical devices. In particular, flexible and lightweight SPSCs are highly desirable in practical applications but are currently restricted by the high annealing temperature needed to make the electron transport layer (ETL) in the devices. Herein, we demonstrate a novel SPSC by integrating a perovskite solar cell (PSC) using amorphous WO_x film deposited at room temperature as ETL and a quasi-solid-state supercapacitor (SC). The WO_x film with 26 nm thickness yielded a champion power conversion efficiency of 14.14% and 10.80% with the FTO/glass rigid and the ITO/PEN flexible PSCs, respectively. Investigation of the performance of the SPSCs based on the rigid substrate (r-SPSC) and the flexible substrate (f- SPSC) exhibited that the r-SPSC could be photo-charged to 0.68 V within 20 s while the f-SPSC required 25 s to be charged to 0.65 V. Consequently, an overall conversion efficiencies of 2.13% and 1.27% were obtained with the r-SPSCs and the f-SPSC, respectively. This work paves a new way towards making SPSCs that may serve as off-grid electrical power supply in the future.