Pre-Embedded Multisite Chiral Molecules Realize Bottom-Up Multilayer Manipulation toward Stable and Efficient Perovskite Solar Cells

The defects from functional layers and interface, the agglomeration of SnO2 nanoparticles (NPs), and poor perovskite crystallization are the main barrier to further heightening the power conversion efficiency (PCE) and stability of regular perovskite solar cells. Here, a bottom-up multilayer manipulation strategy by pre-embedding multisite racemic DL-cysteine hydrochloride monohydrate (DLCH) into the SnO2 electron transport layer (ETL) is reported. The positively and negatively charged defects from ETL, perovskite layer and their interface can be passivated through the synergistic effect of the SH, COOH, NH3+, and Cl- groups in DLCH. The synergy of multiple functional groups and multiple chemical bonds enables bottom-up cross-layer passivation, which minimizes bulk and interfacial nonradiative recombination losses. Furthermore, the multifunctional DLCH plays a role in inhibiting the agglomeration of SnO2 NPs, managing photons, relieving interfacial tensile stress, and manipulating perovskite crystallization. Benefiting from the above advantages, the DLCH-incorporating device delivers a PCE of 24.01%, which is much higher than the 21.61% of the control device. Moreover, the DLCH-modified devices demonstrate inviting thermal and ambient stabilities by maintaining 93% of the initial efficiency after aging at 65 degrees C for 1800 h and 95% of the original PCE after aging under a relative humidity of 20-25% for 2000 h. A bottom-up multilayer manipulation strategy is proposed by pre-embedding multisite racemic DL-cysteine hydrochloride monohydrate (DLCH) into SnO2 electron transport layer. The synergy of multiple functional groups and multiple chemical bonds enables bottom-up cross-layer passivation, which minimizes bulk and interfacial nonradiative recombination losses. The power conversion efficiency is improved from 21.61 to 24.01% after DLCH modulation.image