Overcoming Charge Confinement in Perovskite Quantum Dot Solar Cells.

The small nanoparticle size and long-chain ligands in colloidal metal halide perovskite quantum dots (PeQDs) cause charge confinement, which impedes exciton dissociation and carrier extraction in PeQD solar cells, so they have low short-circuit current density J , which impedes further increases in their power conversion efficiency (PCE). Here, we develop a re-assembling process (RP) for perovskite nanocrystalline (PeNC) films made of PeQDs to increase J in PeQD solar cells. RP of PeNC films increases their crystallite size and eliminates long-chain ligands, and thereby overcomes the charge confinement in PeNC films. These changes facilitate exciton dissociation and increase carrier extraction in PeQD solar cells. By use of this method, the gradient bandgap PeQD solar cells achieve a J = 19.30 mA cm without compromising the photo-voltage, and yielded high PCE = 16.46% with negligible hysteresis and good stability. This work provides a new strategy to process PeNC films and pave a way for high performance PeQD optoelectronic devices. This article is protected by copyright. All rights reserved.