Thiophene-Fused Perylenediimide-Based Polymer Acceptors for High-Performance All-Polymer Solar Cells

Abstract

Over the past years, perylenediimide (PDI)-based polymers have emerged as one of the widely studied polymer acceptors applicable to all-polymer solar cells (PSCs) due to their outstanding photovoltaic properties. Covalently fused PDI units, such as naphthodiperylenetetraimide (NDP), are proven beneficial to increasing the regularity of polymer backbones and enhancing the molecular packing in blend films, thus optimizing the active-layer morphology and improving the device performance. However, most investigated PDI polymers commonly demonstrated low open-circuit voltage (V oc ) in solar cells due to their low-lying lowest unoccupied molecular orbital (LUMO), which greatly limited the power-conversion efficiencies (PCEs) of their devices. Herein, we design and synthesize two new polymer acceptors (PTP-TT and PTP-Th) using thiophene-fused dimeric PDI (i.e., PTP) as the key building block. Both polymers exhibit much elevated LUMO levels at ca. −3.8 eV and achieve higher V oc in devices compared with NDP-derived polymers. In particular, PTP-TT exhibits stronger light-absorption ability than PTP-Th and a presumably more planar backbone conformation, which are favorable for molecular packing and charge carrier transport in the active layer. Using PTB7-Th as the donor, PTP-TT-based devices achieve the best PCE of 7.04%, with a V oc of 0.86 V, a short-circuit current density of 14.96 mA/cm 2 , and a fill factor of 54%. The current results demonstrate that fusing PDIs with a proper electron-rich moiety can synergistically elevate the LUMO level and optimize the backbone regularity of polymer acceptors to obtain desirable efficiencies of PSCs.

Recent advancements in perylene diimide as an electron acceptor in organic solar cells

“…Consequently, when paired with PTB7Th as the donor and utilizing 1-chloronaphthalene (CN) as a solvent additive, PTP-TT achieves a PCE of ∼7.04%. 78 Tetraphenylethylene (TPE) features inherently twisted configurations and is connected to four PDI2 (dimer) units, resulting in TPE-4PDI2. When paired with PTB7-Th, TPE-4PDI2 exhibits a PCE of 7.10%.…”

Unraveling the origin of improved photovoltaic performance in acceptor–acceptor-structured perylene-diimide-based polymeric acceptors through partially fluorinating benzo[c][1,2,5]thiadiazole

“…28 Subsequently, the PCE was increased to 3.04% when choosing PBDTTT-C-T as the donor in 2014 and then was continuously maximized to 3.49% when matched with donor BDDT in 2017. 29,30 Assisted by the design idea of the welldeveloped PDs, substantial efforts devoted to constructing donor-acceptor (D-A) structured alternating conjugated polymers (CPs) via coupling with numerous electron-rich units, i.e., vinylene (V), 26,27,31 fluorene (F), [31][32][33] carbazole (Cz), 31,32 benzo[1,2-b:4,5-b 0 ]dithiophene (BDT), [33][34][35][36] naphtho[1,2-b:5,6b 0 ]dithiophene (NDT), 36 thiophene (T), 25,31,37,38 selenophene (Se), 37,39 tellurophene (Te), 40 bithiophene (2T), [41][42][43] thieno[3,2b]thiophene (TT), [36][37][38] thienylenevinylene (TVT), 44 31 and so on. Apparently, among these PDI-based D-A type CPs, thiophene, tellurophene and vinylene building blocks possessing relatively small volume cubage exhibited an excellent PCE of over 6% (Table S1, ESI †).…”

Diketo-Pyrrolo Pyrrole-Based Acceptor-Acceptor Copolymers with Deep HOMO and LUMO Levels Absorbing in the Near Infrared

“…Among n-type polymers, those based on naphthalene diimide (NDI) and perylene diimide (PDI) are an important series that show good performances in all-polymer solar cells [18][19][20][21][22]. Performances of OSCs combining PDI-based D-A acceptor polymers with adequate p-type polymers achieved power conversion efficiencies (PCE) up to 7% [23]. It has been demonstrated that D-A copolymers based on DPP combined with thiophene or selenophene could exhibit a high photoresponse with a tuneable absorption edge from 950 to 1200 nm, allowing PCE from 2.9% to 5.3% [24].…”