Pronounced Effects of a Triazine Core on Photovoltaic Performance–Efficient Organic Solar Cells Enabled by a PDI Trimer‐Based Small Molecular Acceptor

Choi

Advanced Energy Materials

et al. 2017

102

A wide‐bandgap polymer, (poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(2,5‐(methyl thiophene carboxylate))]) (3MT‐Th), is synthesized to obtain a complementary broad range absorption when harmonized with 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (ITIC). The synthesized regiorandom 3MT‐Th polymer shows good solubility in nonhalogenated solvents. A film of 3MT‐Th:ITIC can be employed for forming an active layer in a polymer solar cell (PSC), with the blend solution containing toluene with 0.25% diphenylether as a nonhalogenated additive. The corresponding PSC devices display a power conversion efficiency of 9.73%. Moreover, the 3MT‐Th‐based PSCs exhibit excellent shelf‐life time of over 1000 h and are operationally stable under continuous light illumination. Therefore, methyl thiophene‐3‐carboxylate in 3MT‐Th is a promising new accepting unit for constructing p‐type polymers used for high‐performance nonfullerene‐type PSCs.

Section: Introductionmentioning

confidence: 99%

Eco‐Friendly Solvent‐Processed Fullerene‐Free Polymer Solar Cells with over 9.7% Efficiency and Long‐Term Performance Stability

Choi

Advanced Energy Materials

et al. 2017

102

“…Designing the narrow bandgap acceptors with NIR absorption matching with mid-bandgap donors could be an ideal case for further improving the PCEs of OSCs. Recently, nonfullerene acceptors (NFAs) [4][5][6][7][8][9][10][11][12] used in OSCs have drawn vigorous attention A new electron-rich central building block, 5,5,12,12-tetrakis(4-hexylphenyl)indacenobis-(dithieno[3,2-b:2′,3′-d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC-4F) are designed and synthesized.…”

mentioning

confidence: 99%

Dithieno[3,2‐b:2′,3′‐d]pyrrol Fused Nonfullerene Acceptors Enabling Over 13% Efficiency for Organic Solar Cells

et al. 2018

A new electron-rich central building block, 5,5,12,12-tetrakis(4-hexylphenyl)-indacenobis-(dithieno[3,2-b:2',3'-d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC-4F) are designed and synthesized. The two molecules reveal broad (600-900 nm) and strong absorption due to the satisfactory electron-donating ability of INP. Compared with its counterpart INPIC, fluorinated nonfullerene acceptor INPIC-4F exhibits a stronger near-infrared absorption with a narrower optical bandgap of 1.39 eV, an improved crystallinity with higher electron mobility, and down-shifted highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Organic solar cells (OSCs) based on INPIC-4F exhibit a high power conversion efficiency (PCE) of 13.13% and a relatively low energy loss of 0.54 eV, which is among the highest efficiencies reported for binary OSCs in the literature. The results demonstrate the great potential of the new INP as an electron-donating building block for constructing high-performance nonfullerene acceptors for OSCs.

Advanced Energy Materials

“…

…”

mentioning

confidence: 99%

Side‐Chain Impact on Molecular Orientation of Organic Semiconductor Acceptors: High Performance Nonfullerene Polymer Solar Cells with Thick Active Layer over 400 nm

Luo

Sun

Chen

et al. 2018

124

In recent years, n-type organic semiconductor (n-OS) (or called as nonfullerene) acceptors have been gaining their popularity in low production cost, light weight, flexible and large-area applications in polymer solar cells (PSCs) due to their excellent optical absorption, tunable energy levels, facile synthesis, and good solution-processability. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Compared with traditional fullerene acceptors such as [6,6]-phenyl-C61/C71-butyric acid methyl ester (PC 61 BM/PC 71 BM), PSCs based on the n-OS acceptors have shown great potential in device performance and device stability. [14,[17][18][19][20][21][22][23][24][25][26][27][28][29] And the n-OS acceptors-based devices have achieved power conversion efficiency (PCE) as high as over 12%. [30][31][32][33][34][35][36][37][38][39][40][41][42] The rational design of the n-OS acceptors is typically based on molecular packing and orbital energetics strategies that are utilized to effectively alter the extension of π conjugation and frontier orbital energy levels. [43][44][45][46][47] Up to now, great efforts have been devoted to development of building blocks, terminal functional groups and side chains, which can effectively tune the band gap and energy levels of the n-OS acceptors. Among them, relatively little attention have been paid to the sidechain engineering of the n-OS acceptors. [5,[48][49][50][51] In comparison with backbone structure and terminal functional groups manipulation, "side-chain engineering" strategy can not only avoid the time-consuming end-capping deficient group and backbone synthesis, but also can improve the photovoltaic performance of PSCs. [33,49,[52][53][54] In addition, this strategy provides an intuitive approach to study the structure-property relationship for the acceptor with the small alterations of the side-chain structures. Structural modification in sidechains of the acceptor, such as changing in length, position, symmetry, and dimension, can remarkably affect molecular packing and intermolecular interaction. [5,[48][49][50][51] For example, the side-chain isomerization of ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4hexylphenyl)-dithieno[2,3-d:2,3-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene) with meta-alkyl-phenyl instead of para-alkyl-phenyl led to the acceptor m-ITIC with more evident crystallinity and higher electron mobility; [48] the replacement of the side chains of rigid indacenodithieno[3,2-b]-thiophene (IDTT) core from 4-hexylphenyl to 5-hexylthienyl downshifts the lowest unoccupied molecular orbital (LUMO) energy levels and improves the A new n-type organic semiconductor (n-OS) acceptor IDTPC with n-hexyl side chains is developed. Compared to side chains with 4-hexylphenyl counterparts (IDTCN), such a design endows the acceptor of IDTPC with higher electron mobility, more ordered face-on molecular packing, and lower band gap. Therefore, the IDTPC-based polymer solar cells (PSCs) with a newly developed wide bandgap polymer PTQ10 as donor exhi...