Dual Defect‐Passivation Using Phthalocyanine for Enhanced Efficiency and Stability of Perovskite Solar Cells

Abstract

Semiconducting molecules have been employed to passivate traps extant in the perovskite film for enhancement of perovskite solar cells (PSCs) efficiency and stability. A molecular design strategy to passivate the defects both on the surface and interior of the CH3NH3PbI3 perovskite layer, using two phthalocyanine (Pc) molecules (NP‐SC6‐ZnPc and NP‐SC6‐TiOPc) is demonstrated. The presence of lone electron pairs on S, N, and O atoms of the Pc molecular structures provides the opportunity for Lewis acid–base interactions with under‐coordinated Pb2+ sites, leading to efficient defect passivation of the perovskite layer. The tendency of both NP‐SC6‐ZnPc and NP‐SC6‐TiOPc to relax on the PbI2 terminated surface of the perovskite layer is also studied using density functional theory (DFT) calculations. The morphology of the perovskite layer is improved due to employing the Pc passivation strategy, resulting in high‐quality thin films with a dense and compact structure and lower surface roughness. Using NP‐SC6‐ZnPc and NP‐SC6‐TiOPc as passivating agents, it is observed considerably enhanced power conversion efficiencies (PCEs), from 17.67% for the PSCs based on the pristine perovskite film to 19.39% for NP‐SC6‐TiOPc passivated devices. Moreover, PSCs fabricated based on the Pc passivation method present a remarkable stability under conditions of high moisture and temperature levels.

Deuterated N,N-dimethylformamide (DMF-d7) as an additive to enhance the CsPbI3 solar cell efficiency

“…Moreover, there are also two small peaks at lower binding energies of 136.8 and 141.6 eV in the blank contrast, indicating the unsaturated coordinated Pb 2+ clusters in the blank contrast film. [41][42][43][44] The highresolution spectrum of Cs 3d shows a similar trend to that of Pb 4f (Fig. S4a, ESI †), and similar conclusions can be drawn.…”

Defect Passivation for Perovskite Solar Cells: from Molecule Design to Device Performance

“…With the continuous progress of PSCs toward high efficiency and stability, increasing the light‐harvesting ability of the perovskite layer also becomes an important function for the passivation molecules [141,142] . So far, the light‐sensitized ruthenium‐based pyridine dyes, porphyrin derivatives, phthalocyanine derivatives, and the narrow‐bandgap organic semiconductors were reported as the passivation agents to expand the photo‐response of PSCs from the ultraviolet (UV) region to the near‐infrared (NIR) region to improve both V OC and J SC [143,144] …”

Effective Interface Defect Passivation via Employing 1‐Methylbenzimidazole for Highly Efficient and Stable Perovskite Solar Cells

“…In addition, they will also act as non‐radiative recombination centers to enhance the trap‐assisted carrier recombination and damage open‐circuit voltage ( V oc ) and PCE, leading to poor photovoltaic performance of PSCs [25–27] . Passivating the defects at the surface and interface to prepare high‐quality perovskite films with low defect density is an effective method to improve the PCE and stability of PSCs and also widely studied at present [28–36] …”

“…The effects of different passivation agents are greatly affected by the chemical structures and contained functional groups. A lager number of passivation agents were used by taking good advantage of the chemical characteristics to heal different types of defects both at the surface and interface [28–30] . Wang et al.…”

“…Hu et al. carried out a dual defect‐passivation by employing phthalocyanine via Lewis acid‐base interactions with under‐coordinated Pb 2+ sites to enhance the PCE and stability of PSCs [29] . Kang et al.…”