High-Performance Near-Infrared Absorbing n-Type Porphyrin Acceptor for Organic Solar Cells

Abstract

While the outstanding charge transport and sunlightharvesting properties of porphyrin molecules are highly attractive as active materials for organic photovoltaic (OPV) devices, the development of ntype porphyrin-based electron acceptors has been challenging. In this work, we developed a high-performance porphyrin-based electron acceptor for OPVs by substitution of four naphthalene diimide (NDI) units at the perimeter of a Zn-porphyrin (P Zn ) core using ethyne linkage. Effective πconjugation between four NDI wings and the P Zn core significantly broadened Q-band absorption to the near infrared region, thereby achieving the narrow band gap of 1.33 eV. Employing a windmill-structured tetra-NDI substituted P Zn -based acceptor (P Zn -TNDI) and mid-band gap polymer donor (PTB7-Th), the bulk heterojunction OPV devices achieved a power conversion efficiency (PCE) of 8.15% with an energy loss of 0.61 eV. The PCE of our P Zn -TNDI-based device was the highest among the reported OPVs using porphyrin-based acceptors. Notably, the amorphous characteristic of P Zn -TNDI enabled optimization of the device performance without using any additive, which should make industrial fabrication simpler and cheaper.

Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes

“…Furthermore, they found that the introduction of alkyl chains on porphyrin enhanced the aggregation of these porphyrin‐based molecules compared with aromatic side groups, which had a significant influence on physicochemical properties such as electrochemical behavior, crystallinity, and nonradiative recombination loss. Hadmojo et al synthesized a porphyrin‐based small molecule, P Zn ‐TNDI, by introducing four naphthalene diimide (NDI) units to the perimeter of the zinc porphyrin core via ethyne linkages . Benefiting from the effective ICT between porphyrin and NDI, the molecule exhibits a low bandgap of 1.33 eV.…”

Inducing Open-Shell Character in Porphyrins through Surface-Assisted Phenalenyl π-Extension

“…4 Among such structural modifications, the π-extension of the Por core is particularly appealing, since it leads to compounds with a strong near-infrared (NIR) absorption, stemming from a small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap. 12 Such π-extended Pors can be obtained either by attaching other aromatic units to the macrocycle via conjugative linkers 9,[13][14][15][16] or through the meso,β-fusion of aromatic units via intramolecular oxidative coupling. [17][18][19][20][21][22][23][24] Using the latter synthetic strategy, a wide range of π-extended Pors has been reported, showing, in some cases, absorptions reaching far into the NIR region (i.e., 1417 nm) and optical HOMO- LUMO gaps as low as 0.61 eV.…”

Inducing Open-shell Character in Porphyrins through Surface-assisted Phenalenyl π−Extension

“…4 Among such structural modifications, the π-extension of the Por core is particularly appealing, since it leads to compounds with a strong near-infrared (NIR) absorption, stemming from a small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap. 12 Such π-extended Pors can be obtained either by attaching other aromatic units to the macrocycle via conjugative linkers 9,[13][14][15][16] or through the meso,β-fusion of aromatic units via intramolecular oxidative coupling. [17][18][19][20][21][22][23][24] Using the latter synthetic strategy, a wide range of π-extended Pors has been reported, showing, in some cases, absorptions reaching far into the NIR region (i.e., 1417 nm) and optical HOMO- LUMO gaps as low as 0.61 eV.…”