Indene−C₆₀Bisadduct: A New Acceptor for High-Performance Polymer Solar Cells

TLDR

Polymer solar cells typically use a donor polymer blended with a soluble C60 derivative acceptor, with P3HT and PCBM being the most common pair, but PCBM’s low LUMO limits the open‑circuit voltage to about 0.6 V. The authors aimed to synthesize a new soluble C60 derivative, indene‑C60 bisadduct (ICBA), whose higher LUMO energy could raise the device Voc. ICBA was designed with a LUMO 0.17 eV higher than PCBM, enabling its use as an acceptor in P3HT‑based PSCs. P3HT/ICBA devices achieved a Voc of 0.84 V and a PCE of 5.44 %, outperforming P3HT/PCBM devices (Voc 0.58 V, PCE 3.88 %) and demonstrating ICBA as a high‑performance acceptor.

Abstract

Polymer solar cells (PSCs) are commonly composed of a blend film of a conjugated polymer donor and a soluble C60 derivative acceptor sandwiched between an ITO anode and a low-workfunction metal cathode. Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are the most widely used donor and acceptor materials, respectively. However, the low LUMO energy level of PCBM limits the open circuit voltage (Voc) of the P3HT-based PSCs to ca. 0.6 V. Here we synthesized a new soluble C60 derivative, indene−C60 bisadduct (ICBA), with a LUMO energy level 0.17 eV higher than that of PCBM. The PSC based on P3HT with ICBA as acceptor shows a higher Voc of 0.84 V and higher power conversion efficiency (PCE) of 5.44% under the illumination of AM1.5, 100 mW/cm2, while the PSC based on P3HT/PCBM displays a Voc of 0.58 V and PCE of 3.88% under the same experimental conditions. The results indicate that ICBA is an alternative high-performance acceptor and could be widely used in high-performance PSCs.