Abstract
Charged defects at the surface of the organic–inorganic perovskite active layer are detrimental to solar cells due to exacerbated charge carrier recombination. Here we show that charged surface defects can be benign after passivation and further exploited for reconfiguration of interfacial energy band structure. Based on the electrostatic interaction between oppositely charged ions, Lewis-acid-featured fullerene skeleton after iodide ionization (PCBB-3N-3I) not only efficiently passivates positively charged surface defects but also assembles on top of the perovskite active layer with preferred orientation. Consequently, PCBB-3N-3I with a strong molecular electric dipole forms a dipole interlayer to reconfigure interfacial energy band structure, leading to enhanced built-in potential and charge collection. As a result, inverted structure planar heterojunction perovskite solar cells exhibit the promising power conversion efficiency of 21.1% and robust ambient stability. This work opens up a new window to boost perovskite solar cells via rational exploitation of charged defects beyond passivation.
Highlights
Charged defects at the surface of the organic–inorganic perovskite active layer are detrimental to solar cells due to exacerbated charge carrier recombination
The inverted structure planar heterojunction pero-SCs were constructed with a structure of indium tin oxide (ITO)/poly(triarylamine) (PTAA)/MAPbI3/phenyl-C61-butyric acid methyl ester (PCBM)/Al with and without PCBB-3N-3I/PCBB-3N treatment on MAPbI3 as detailed in the Methods section
Our work opens up a possibility for material and interface design based on the charged surface defects in pero-SCs
Summary
The device was very sensitive to the concentration of PCBB3N-3I or PCBB-3N (Supplementary Tables 1 and 2), where an extremely low concentration (0.1 mg mL−1) gave the superior device performance For this optimized concentration, the resulting PCBB-3N-3I or PCBB-3N film on the rough perovskite surface appears ultrathin or could even be discontinuous. The integrated Jsc from the EQE spectra were 21.56, 22.96, and 20.79 mA cm−2 for the control, PCBB-3N-3I, and PCBB-3N devices, respectively, agreeing well with the Jsc values obtained from the J–V curves within 5% deviation. This sequence in PCEs was further confirmed by their corresponding stabilized PCEs at a maximum power point (MPP) (Supplementary Fig. 6)
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