Perovskite Solar Cells with Front Surface Gradient

The recombination flux in a solar cell is determined by not only recombination centers, but also the spatial distribution of minority carriers. For halide perovskite solar cells (PSCs), although there has been a tremendous amount of work focusing on defect passivation, the issue of carrier distribution is not as well studied as for other types of solar cells. Here in this work, with the incorporation of perovskite quantum dots, the concept of the front surface gradient in PSCs using a solution process is successfully realized. Evidenced by multiple characterization techniques, the minority carriers are pushed away from the defect-rich surface by the gradient of valence band maximum, which effectively reduces surface recombination without compromising photocurrent. As a result, the normal structured hybrid PSCs and MAPbI(3) cells exhibit open-circuit voltages exceeding 93% and 90% of their respective Shockley-Queisser limits, and the power conversion efficiencies reach 22.36% and 20.53%, respectively.

Automated summary

The study investigated carrier distribution in halide perovskite solar cells and successfully achieved a gradient structure using perovskite quantum dots, effectively reducing surface recombination without compromising photocurrent. The performance of normal structured hybrid PSCs and MAPbI(3) cells was found to be good, with open-circuit voltages exceeding their respective Shockley-Queisser limits and power conversion efficiencies reaching up to 22.36% and 20.53%, respectively.