High Yield Synthesis of Water‐Processable Donor:Acceptor Janus Nanoparticles with Tuned Internal Morphology and Highly Efficient Charge Separation/Transfer

Abstract

Here, for the first time, the high‐yield (87.6%) robust and facile synthesis of water‐processable donor–acceptor Janus nanoparticles (JNP) that are of high potential for optoelectronic applications is reported. The water‐processable JNPs have easily controlled Janus ratios and are of excellent quality, which is shown by energy‐filtered transmission electron microscopy. The JNPs exhibit improved charge separation and transfer properties compared to the conventional donor–acceptor nanoparticles which is characterized via both steady‐state and transient photoluminescence spectroscopy. The Janus character of particles allows the combination of two materials into one composite and programs morphology of structures, which can be formed on the basis of the particles. Finally, outstanding performance of JNP‐based photovoltaic cells with 53% improvement of efficiency is shown.

Donor:Acceptor Janus Nanoparticle‐Based Films as Photoactive Layers: Control of Assembly and Impact on Performance of Devices

“…In our previous work, high‐quality pure PTB7, pure PC 71 BM, PTB7:PC 71 BM core–shell, and Janus NPs were synthesized. [ 31 ] To prove the universality of our self‐assembly strategy, these two different NPs (PC 71 BM‐core:PTB7‐shell (PC 71 BM‐c:PTB7‐s) NPs and PTB7:PC 71 BM Janus NPs) and pure donor/acceptor NPs (PTB7 NPs and PC 71 BM NPs) were performed to apply this method afterward (Figure S8, Supporting Information).…”

“…Synthesis of Pure Donor and Acceptor NP Dispersions: The synthesis process of PTB7 or PC 71 BM NPs was introduced in the authors' previous work. [31] Briefly, 5 mg of PTB7 or 5 mg of PC 71 BM was dissolved in 1 mL of chloroform with continuous stirring at 50 °C overnight. Then, 5 mL SDS solution (34.7 mm) in deionized water was rapidly injected into the organic solution.…”

“…First, the D:A nanoparticles (NPs) were fabricated via the mini-emulsion process as described elsewhere. [30,31] These water-processable NPs consisting of polymer donor poly[ [4,8bis[(2-ethylhexyl)oxy]benzo [1,2- [3,4-b]thiophenediyl]] (PTB7) were matched with the fullerene acceptor ( [6,6]-Phenyl-C71-butyric acid methyl ester) (PC 71 BM) (Figure 1a). The obtained NPs were monodispersed in a spherical structure, around 80 nm (Figure 1b).…”

Sub-4 nm mapping of donor–acceptor organic semiconductor nanoparticle composition

“…Nanoengineering strategies for producing Janus morphologies for applications in OPV have only recently been reported. 30,61 It is theorised that the Janus nanoparticle morphology could become the ideal morphology for OPV (and for photocatalytic applications) because Janus nanoparticles of small diameters (<30 nm) could combine high exciton dissociation rate and perfect conduction pathways for both charges. 12 Therefore, the OPV field needs strategies to carefully tune the nanomorphology of donor-acceptor nanoparticles and powerful techniques, such as STEM EDX, to confirm their morphologies which will define the device performance.…”

“…[25][26][27][28][29] Cryo-TEM has high spatial resolution, sufficient for mapping domains within organic nanoparticles, but lacks chemical sensitivity. It is only suitable where one material is crystalline, which affords the use of regular lattice spacing for indication of domains of each material, as was demonstrated for the PTB7-Th:eh-IDTBR system by Kosco et al 13 Energy-filtered TEM (EFTEM) and STEM energy-loss spectroscopy (EELS) mapping of organic donor : acceptor nanoparticles 30,31 and BHJ 32 films has, on the other hand, been reported. However, reports were each limited to a single polymer:fullerene material system, and a high spatial resolution for mapping the internal compositional structure of nanoparticles was not achieved.…”