Dual Modification Engineering via Lanthanide-Based Halide Quantum Dots and Black Phosphorus Enabled Efficient Perovskite Solar Cells with High Open-Voltage of 1.235 V

Interfacial engineering is one of the most effective means to improve the photoelectric conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In this work, Ln(3+)-based halide Cs3TbCl6 quantum dots (QDs) are synthesized through a modified hot-injection method, which displays an excitonic emission centered at 431 nm and the characteristic emission peaks of Tb3+ ions. Then, the Ln(3+)-based halide Cs3TbCl6 QDs are introduced to the interface of Cs-0.05(FA(0.83)MA(0.17))(0.95)Pb(I0.83Br0.17)(3) perovskite films in the PSCs, which can regulate the energy levels, fill the grain boundaries and remove the ionic defects. Surprisingly, the Cs3TbCl6 QDs modified devices achieve a champion PCE of 22.89% with a super high open-voltage of 1.235 V. The high open-voltage can be mainly attributed to the better bandgap alignment, enhanced interface, and reduced defects density. Afterward, the hole transport layer (HTL) is modified by the black phosphorus QDs (BPQDs), yielding a champion PCE of 23.49% and a filling factor of 80.32%. The Cs3TbCl6 QDs modified unencapsulated device possesses well environmental stability and humidity stability. This work demonstrates a new kind of Ln(3+)-based metal QDs and explores a new approach to fabricate the PSCs with high open-voltage, high efficiency, and good stability through the QD-based passivation techniques.

Automated summary

Interfacial engineering with Ln(3+)-based halide quantum dots can significantly enhance the performance and stability of perovskite solar cells, achieving high open voltage and efficiency.