Porphyrinic Metal-Organic Framework Quantum Dots for Stable n-i-p Perovskite Solar Cells

As the power-conversion efficiency (PCE) of organic-inorganic lead halide perovskite solar cells (PSCs) is approaching the theoretical maximum, the most crucial issue concerns long-term ambient stability. Here, the application of PCN-224 quantum dots (QDs) is reported, a typical Zr-based porphyrinic metal-organic framework (MOF), to enhance the ambient stability of PSCs. PCN-224 QDs with abundant Lewis-base groups (e.g., C(sic)O, C-N, C(sic)N) contribute to high-quality perovskite films with enlarged grain size and reduced defect density by interaction with under-coordinated Pb2+. Meanwhile, PCN-224 QDs enable the well-matched energy level at the perovskite/hole transport layer (HTL) interface, thereby facilitating hole extraction and transport. More importantly, PCN-224 QDs-treated HTL can capture Li+ from bis(trifluoromethanesulfonyl)imide additive, leading to the reduced aggregation and less direct contact with moisture for hygroscopic Li-TFSI. Moreover, PCN-224 QDs mitigated Li+ ion migration into the perovskite layer, thus avoiding the formation of deleterious defects. The resultant devices yield a champion PCE of 22.51%, along with substantially improved durability, including humidity, thermal and light soaking stabilities. The findings provide a new approach toward efficient and stable PSCs by applying MOF QDs.

Automated summary

This study reports the use of PCN-224 quantum dots (QDs), a typical Zr-based porphyrinic metal-organic framework (MOF), to enhance the ambient stability of organic-inorganic lead halide perovskite solar cells (PSCs). PCN-224 QDs contribute to high-quality perovskite films and facilitate hole extraction and transport at the perovskite/hole transport layer (HTL) interface. Additionally, PCN-224 QDs mitigate Li+ ion migration and reduce the formation of deleterious defects in the perovskite layer. The resulting devices exhibit improved durability and achieve a high power-conversion efficiency (PCE) of 22.51%.