A new strategy for efficient light management in inverted perovskite solar cell

[Display omitted] •Functional structure design of NiO HTLs realize the efficient light management.•The improved light harvesting efficiency contribute to high Jsc of 24.41 mA/cm2.•The obtained 20.40% is among the highest PCEs for NiO inverted devices so far. The light management is of vital importance for development of efficient inverted perovskite solar cells (PSCs), which could maximize the light trapping and minimize optical loss. Herein, a novelly-designed, functional spherical NiO hole transporting layer (HTL) is reported for the first time to effectively increase light utilization and the final photocurrent of inverted MAPbI3 PSCs. Experimental and theoretical results indicate that such hollow NiO HTLs improves optical field distribution and light harvesting efficiency. This contributes to realize the better light utilization and higher photocurrent of over 24 mA cm−2, which is one of the highest reported values for NiO-based MAPbI3 PSCs. Besides, the synergistic Cu doping strategy was further employed to ensure the enhanced hole extraction and suppressed recombination loss. Eventually, this hollow Cu:NiOx PSCs feature desirable efficiency over 20%, along with the improved open-circuit voltage and low hysteresis. This work demonstrates the necessity of light management and unveils a simple approach for achieving efficient inverted NiO-based devices.