Cost-Effective Schiff-Base Nickel Complexes as Cathode Interlayers for High-Efficiency Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Efficient cathode interlayers (CILs) are critical for optimizing bulk-heterojunction organic solar cells (BHJ-OSCs).
• Existing CILs face challenges in performance and cost, necessitating the development of novel materials.

Purpose of the Study:

• To synthesize and characterize novel, low-cost Schiff-base nickel complexes as CILs for BHJ-OSCs.
• To evaluate the performance of these new CILs in comparison to state-of-the-art materials.

Main Methods:

• Synthesis of Ni-Me, Ni-iPr, and Ni-tBu Schiff-base nickel complexes via efficient reactions and simple purification.
• Characterization of CIL properties including work function, film-forming ability, electron conductivity, and electron mobility.
• Device fabrication and performance testing of BHJ-OSCs using the synthesized CILs.

Main Results:

• Ni-Me exhibited superior electron conductivity (6.5 × 10⁻⁴ S cm⁻¹) and electron mobility (5.1 × 10⁻⁴ cm² V⁻¹ S⁻¹).
• Ni-Me demonstrated higher crystallinity compared to Ni-iPr and Ni-tBu.
• BHJ-OSCs with Ni-Me CIL achieved a power conversion efficiency (PCE) of 19.11%, surpassing PDINN (18.52%) and PNDIT-F3N (18.5%).
• Ni-Me CIL showed excellent universality across different OSC active layer compositions.

Conclusions:

• Schiff-base nickel complexes, particularly Ni-Me, are promising low-cost and high-performance CILs for OSCs.
• Ni-Me offers enhanced electronic properties and device performance compared to established CILs.
• These findings highlight the potential of Schiff-base nickel complexes in advancing organic solar cell technology.