Influence of Molecular Geometry of Perylene Diimide Dimers and Polymers on Bulk Heterojunction Morphology Toward High‐Performance Nonfullerene Polymer Solar Cells

Abstract

In this study, we investigate the influence of molecular geometry of the donor polymers and the perylene diimide dimers (di‐PDIs) on the bulk heterojunction (BHJ) morphology in the nonfullerene polymer solar cells (PSCs). The results reveal that the pseudo 2D conjugated poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PTB7‐Th) has better miscibility with both bay‐linked di‐PDI (B‐di‐PDI) and hydrazine‐linked di‐PDI (H‐di‐PDI) compared to its 1D analog, poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]] (PTB7), to facilitate more efficient exciton dissociation in the BHJ films. However, the face‐on oriented π–π stacking of PTB7‐Th is severely disrupted by the B‐di‐PDI due to its more flexible structure. On the contrary, the face‐on oriented π–π stacking is only slightly disrupted by the H‐di‐PDI, which has a more rigid structure to provide suitable percolation pathways for charge transport. As a result, a very high power conversion efficiency (PCE) of 6.41% is achieved in the PTB7‐Th:H‐di‐PDI derived device. This study shows that it is critical to pair suitable polymer donor and di‐PDI‐based acceptor to obtain proper BHJ morphology for achieving high PCE in the nonfullerene PSCs.

Perylene Diimide Trimers Based Bulk Heterojunction Organic Solar Cells with Efficiency over 7%

“…[ 29 ] In this case, the PDI units are oriented perpendicularly to each other through an N N bond, hence we named these PDIs derivatives as Hn -PDI, where n is the number of repeat PDI units. [ 31 ] Obviously, the Hn -PDI-based devices have similar photovoltaic performance to those of the bay-position linked PDIs. [ 31 ] Obviously, the Hn -PDI-based devices have similar photovoltaic performance to those of the bay-position linked PDIs.…”

Potential of Nonfullerene Small Molecules with High Photovoltaic Performance

“…The Ta nd Se bridges increased the electron density and formed am ore twisted configuration that led to ah igher LUMO energy.B ecause of this, the PDBT-T1/SdiPDI-Ses olarc ell, which is one of the most efficient devices based on PDIs, showed ah igh PCE of 8.4 %w ith a V OC of 0.96 V. Head-linked H-diPDI, with at wist angle of 908,s howed ah igh PCE of 6.41 %w hen www.chemasianj.org blended with PTB7-Th. [38,39] The deviceb ased on H-tri-PDI, which consists of three PDI blocks linked through the imide position, showedahigherP CE of 7.25 %w ith a J SC of 16.5 mA cm À2 . [40] Nuckolls et al synthesized as eries of helical PDI oligomers (hPDIn) that showedincreased absorption ability and reduced aggregation as the length of the molecule increased.…”

Impact of Fluorine Atoms on Perylene Diimide Derivative for Fullerene‐Free Organic Photovoltaics

“…[9,10] Among the variousn on-fullerene acceptors, perylenediimide (PDI) based SM were widely investigated because of their intense light absorption,h igh electron mobility and good thermals tability and PCEs of BHJ OPV devices highert han 8% have been achieved. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] As PDI is of ab ig pconjugated planar structure, it is easy to form large size aggregates in the films and such ab ehavior will dramatically affect the exciton dissociation and charge transport, andt hus the device efficiency.T oc ontrol the aggregates of PDI-based molecules and the BHJ film morphologyt of orm appropriate nanostructures and phase separation is key for PDI-based OPVs. [28][29][30] Althoughd evice engineering through optimizing device fabrication processing such as thermal/solventa nnealing or introducinga dditives can improvet he morphologyo fP DI-based OPVs to some extent, such ap rocess does not have universal applicability.…”

“…Notably,t he PL of PTB7-Th and FPDI-CDTph2F are almostt otally quenched in the blend film of PTB7-Th/FPDI-CDTph2F indicating more efficient photon induced charge transfer between PTB7-Th and FPDI-CDTph2F than that in the blend film of PTB7-Th and FPDI-CDTph. [14] The photovoltaic properties of the FPDI acceptors were examined by fabricating OPVs with the following structure:I TO/ PEDOT:PSS/PTB7-Th:FPDIs/PDIN/Al (Figure 3). PTB7-Th was used as the donor,P EDOT:PSS was used as ah ole injection layer and N,N'-bis(propylenedimethylamine)-3,4:9,10-perylenediimide( PDIN) was used as ac athode interlayer.T he energy levels of the layers are shown in Figure 3b.T he optimized D/A weightr atio of PTB7-Th/FPDIs was found to be 1:1.5.…”