Aqueous Nanoparticle Polymer Solar Cells: Effects of Surfactant Concentration and Processing on Device Performance

Abstract

Polymer solar cells based on PDPP5T and PCBM as donor and acceptor materials, respectively, were processed from aqueous nanoparticle dispersions. Careful monitoring and optimization of the concentration of free and surface-bound surfactants in the dispersion, by measuring the conductivity and ζ-potential, is essential to avoid aggregation of nanoparticles at low concentration and dewetting of the film at high concentration. The surfactant concentration is crucial for creating reproducible processing conditions that aid in further developing aqueous nanoparticle processed solar cells. In addition, the effects of adding ethanol, of aging the dispersion, and of replacing [60]PCBM with [70]PCBM to enhance light absorption were studied. The highest power conversion efficiencies (PCEs) obtained are 2.0% for [60]PCBM and 2.4% for [70]PCBM-based devices. These PCEs are limited by bimolecular recombination of photogenerated charges. Cryo-TEM reveals that the two components phase separate in the nanoparticles, forming a PCBM-rich core and a PDPP5T-rich shell and causing a nonoptimal film morphology.

Environmentally friendly preparation of nanoparticles for organic photovoltaics

“…To minimise unwanted SDS from negatively impacting the device performance 27 , centrifugal dialysis was introduced to remove excess free surfactant in the dispersion as well as concentrate the active materials in the water dispersion, giving the final dispersion a solids content of 6 wt% in 0.5 mL water.…”

“…[35][36] This suggests that the performance of PTNT:PC 71 BM NP solar cells is mainly limited by the lower current and lower FF, both of which can be highly dependent on the NP film morphology and the nature of the donor/acceptor interface. 27 Furthermore, compared to solution-processed BHJ solar cells 35 , the lower performance of NP devices could be explained by the relatively isolated polymer and PC 71 BM domains with insufficient connection of fullerene-rich core, which impedes the charge separation 62 as well as increasing the possibility of non-geminate recombination 63 . (Fig.…”

“…[18][19][20] OPVs with active layers processed from a water or alcohol based nanoparticle dispersion has been reported in recent years. [21][22][23][24] These nanoparticles are processed from donor-acceptor blends either through a miniemulsion process with the presence of surfactant [25][26][27][28] or a precipitation method [21][22][23]29 . Furthermore, conjugated polymer nanoparticles were also reported to be synthesized by direct Suzuki-Miyaura dispersion polymerization.…”

Overcoming Microstructural Limitations in Water Processed Organic Solar Cells by Engineering Customized Nanoparticulate Inks

“…A PCE of only 3.8% is the highest performance reported to date [15] and only slightly higher efficiencies of 4% were reported for alcohol-based poly (3-hexylthiophene) (P3HT)/ indene C60-bisadduct (ICBA) nanoparticles synthesized via precipitation. [17] Thermal posttreatment is another mandatory process criteria to break up the polymer shell and melt particles into a continuous interconnected film. The first and foremost consideration is the elimination of the residual surfactant and the reduction of the surfactant stabilizing the nanoparticles.…”

Unique p–n Heterostructured Water‐Borne Nanoparticles Exhibiting Impressive Charge‐Separation Ability

“…[4,5] In particular, p-n heterostructured water-based colloids are of interest for the design of next-generation photovoltaic and electronic devices owing to their photoinduced charge-separationp roperties. [6] The groups of Janssen, [7] Belcher, [8] and Arias [9] used diketopyrrolopyrrole-quinquethiophene alternating copolymer (PDPP5T), poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and poly[{2,6-(4,8-didodecylbenzo [1,2-b:4,5-b']dithiophene)}-alt-{5,5-(2,5bis(2-butyloctyl)-3,6-dithiophen-2-yl-2,5dihydropyrrolo [3,4c]57pyrrole-1,4-dione)}] (PTBT-DPP), respectively,f or the p-type polymerc omponent with the same n-type PCBM, and they obtained PCEs over 2%.T hese device performances,h owever,a re still much lower than those of chlorinated-processed bulk heterojunction solar cells. [6] The groups of Janssen, [7] Belcher, [8] and Arias [9] used diketopyrrolopyrrole-quinquethiophene alternating copolymer (PDPP5T), poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and poly[{2,6-(4,8-didodecylbenzo [1,2-b:4,5-b']dithiophene)}-alt-{5,5-(2,5bis(2-butyloctyl)-3,6-dithiophen-2-yl-2,5dihydropyrrolo [3,4c]57pyrrole-1,4-dione)}] (PTBT-DPP), respectively,f or the p-type polymerc omponent with the same n-type PCBM, and they obtained PCEs over 2%.T hese device performances,h owever,a re still much lower than those of chlorinated-processed bulk heterojunction solar cells.…”