All-small-molecule organic solar cells with over 14% efficiency by optimizing hierarchical morphologies

Abstract

The high efficiency all-small-molecule organic solar cells (OSCs) normally require optimized morphology in their bulk heterojunction active layers. Herein, a small-molecule donor is designed and synthesized, and single-crystal structural analyses reveal its explicit molecular planarity and compact intermolecular packing. A promising narrow bandgap small-molecule with absorption edge of more than 930 nm along with our home-designed small molecule is selected as electron acceptors. To the best of our knowledge, the binary all-small-molecule OSCs achieve the highest efficiency of 14.34% by optimizing their hierarchical morphologies, in which the donor or acceptor rich domains with size up to ca. 70 nm, and the donor crystals of tens of nanometers, together with the donor-acceptor blending, are proved coexisting in the hierarchical large domain. All-small-molecule photovoltaic system shows its promising for high performance OSCs, and our study is likely to lead to insights in relations between bulk heterojunction structure and photovoltaic performance.

15.3% efficiency all-small-molecule organic solar cells enabled by symmetric phenyl substitution

“…In recent studies, notable progress has been made in donor molecule design to develop small-molecule donors for NFSM-OSCs. One of them is enlarging the coplanar core and extending the conjugation length to regulate the donor structure and render NFSM-OSCs optimized hierarchical morphologies to obtain certified PCE over 14% [27]. The other is halogenation, which means to introduce fluorine, chlorine or bromine atoms to the specific positions of some representative units to adjust the energy levels and crystalline properties of the small molecule donor.…”

Diketopyrrolopyrrole linked porphyrin dimers for visible-near-infrared photoresponsive nonfullerene organic solar cells

“…8,23,24 However, SM donors sporadically succeeded with several advantages such as high crystallinity, rapid aggregation pathways, controllable energy levels, etc., and as a result, assisting the significant enhancement of PCEs in recent years. [25][26][27][28][29][30][31][32][33][34][35][36][37][38] However, the combination of a SM donor and a SM acceptor has been a bottleneck hindering the performance so far due to their high crystallinity and unfavourable phase separation and morphologies. 25,39 Recently, Wei et al reported an A-p-D-p-A structural narrow bandgap SM donor based on a larger coplanar core DTBDT and achieved the highest PCE of 14.34% at that time for binary all SM OSCs by optimizing their hierarchical morphologies.…”

“…25,39 Recently, Wei et al reported an A-p-D-p-A structural narrow bandgap SM donor based on a larger coplanar core DTBDT and achieved the highest PCE of 14.34% at that time for binary all SM OSCs by optimizing their hierarchical morphologies. 35 This significant success has led to an enhanced performance of all SM donors and acceptors which are comparable to that of NF-OSCs based on polymer donors. However, there are still very limited SM donors developed with the combination of NF acceptors for all SM-OSCs and those are with a fully responsive spectrum in the visible-NIR region.…”

Tetrabromination versus Tetrachlorination: A Molecular Terminal Engineering of Nonfluorinated Acceptors to Control Aggregation for Highly Efficient Polymer Solar Cells with Increased Voc and Higher Jsc Simultaneously

“…[ 1–12 ] Compared with traditional fullerene acceptors, A–D–A framework nonfullerene small molecular acceptors (NF‐SMAs) have significant advantages in broader absorption range, tunable molecular structure and energy levels, and diversified donor materials for matching. [ 13–23 ] Therefore, many such typed NF‐SMAs have been synthesized and become the mainstream materials for the development of high‐efficiency PSCs. [ 24–36 ] Recently, the power conversion efficiencies (PCEs) of NF‐SMAs‐based PSCs have been sharply increased over 16% in single‐junction binary and ternary devices, indicating their great potentials for further practical application.…”