A perylene diimide (PDI) flanked diketopyrrolopyrrole (DPP) π-conjugated small molecule has been synthesized through an efficient and sustainable direct heteroarylation protocol. When paired with the donor polymer PTB7-Th, air-processed and tested bulk-heterojunction (BHJ) organic solar cells (OSCs) achieved a high power conversion efficiency (PCE) of 5.6%. The new acceptor showed favorable morphological changes upon solvent vapor annealing leading to a near 3-fold increase in PCE. This result is among the best reported utilizing DPP-based acceptors in air-processed and tested OSCs. All solar cells exhibited good air and light stability over a 35-day evaluation period.

In recent years, the intensive development of π-conjugated small molecule acceptors has yielded viable alternatives to fullerene acceptors in state-of-the-art organic photovoltaic devices. Small molecule acceptors are designed to replicate the favourable electronic properties of fullerenes and to overcome their inherent optical and stability deficiencies. Concurrently, advances in device engineering through rigorous optimization have seen the development of intricate device architectures and led to impressive performance increases. This review highlights a number of recent high performance non-fullerene acceptors, focusing on the design of π-conjugated structures, device optimization and the ensuing power conversion efficiencies.

Demonstration of the utility of a commercially available heterogeneous palladium catalyst in the synthesis of a relevant high performance molecular semiconductor.

A streamlined synthetic approach to easily access complex pi-conjugated molecular materials.