Tunable organic PV parallel tandem with ionic gating

Saranin, Danila; Ishteev, A.; Cook, Alexander; Yuen, Jonathan D.; Кузнецов, Денис; Orlova, Marina; Didenko, S.; Zakhidov, Anvar A.

doi:10.1063/1.4979900

Cited by 8 publications

(14 citation statements)

References 39 publications

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“…It was considered that both the type and size of the anion play critical roles in the polarizability and adsorption of the ions at the materials interfaces. The experimental studies demonstrated the order of carrier injection efficiency for the widely used ILs: BMIM-OTf > DEME-TFSI > BMIM-TFSI > DEME-BF4 > BMIM-BF4 > BMIM-PF6. , We have chosen DEME-BF4 as an exemplary IL in our current studies since it has one of the largest voltage stability window and since it was used in our earlier studies of gating in BHJ OPV. ,, On the other hand, different ILs have been tested as well, such as BMIM-BF4 and BMIM-PF6 for ionically gated hybrid PVs, and a separate paper is in preparation. While results on IL effects for the case of BMIM are indeed different from that of DEME-BF4, they are beyond the scope of this paper, but some differences are shortly described in the Supporting Information (Section S6).…”

Section: Methodsmentioning

confidence: 99%

“…So, the initial motivation of our present paper is to create a small-molecule OPV device in which n-doping can be easily achieved in a system of porous CNT electrodes coated on top of the fullerene film ETL of a most simple two-layer OPV: CuPc/fullerene with the methods of reversible ionic EDLC. This requires a new architecture which combines an IL supercapacitor, connected in parallel with OPV as we introduced earlier for a polymeric OPV with IL and demonstrated its advantages in tandems …”

Section: Introductionmentioning

confidence: 99%

“…We show here that this process differs significantly from the case of polymeric OPVs, studied in our earlier paper, since in a thick molecular fullerene film (with molecules bonded by van der Waals forces), there are clearly three stages of charging and n-doping of MWCNT and fullerene subsystems separately. The main motivation of this study is to compare the ionic gating effect on the two traditional architectures used in OPVs with the aim to understand how the planar geometry of layers, particularly thick ETLs, by C 60 and C 70 in a small-molecule OPV is different from the BHJ geometry of the interpenetrating D–A networks used in most polymeric OPVs (already studied by the ionic gating effect in refs and ). Therefore, the emphasis is on the CuPc/C 60 small-molecule OPV (which has intentionally not optimized low PCE due to an unusually thick fullerene ETL), while the BHJ-OPV of PTB7–PCBM-type OPV is described in less detail (with details found in the Supporting Information and in ref ) since already the main effects in BHJ are described.…”

Section: Introductionmentioning

confidence: 99%

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Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Saranin

Mahmoodpoor

Voroshilov

et al. 2021

ACS Appl. Mater. Interfaces

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We demonstrate an improvement in the performance of organic photovoltaic (OPV) systems based on small molecules by ionic gating via controlled reversible n-doping of multi-wall carbon nanotubes (MWCNTs) coated on fullerene electron transport layers (ETLs): C60 and C70. Such electric double-layer charging (EDLC) doping, achieved by ionic liquid (IL) charging, allows tuning of the electronic concentration in MWCNTs and the fullerene planar acceptor layers, increasing it by orders of magnitude. This leads to the decrease of the series and increase of the shunt resistances of OPVs and allows use of thick (up to 200 nm) ETLs, increasing the durability of OPVs. Two stages of OPV enhancement are described upon the increase of gating bias V g: at small (or even zero) V g, the extended interface of ILs and porous transparent MWCNTs is charged by gating, and the fullerene charge collector is significantly improved, becoming an ohmic contact. This changes the S-shaped J–V curve via improving the electron collection by an n-doped MWCNT cathode with an ohmic interfacial contact. The J–V curves further improve at higher gating bias V g due to the increase of the Fermi level and decrease of the MWCNT work function. At the next qualitative stage, the acceptor fullerene layer becomes n-doped by electron injection from MWCNTs while ions of ILs penetrate into the fullerene. At this step, the internal built-in field is created within OPV, which helps in exciton dissociation and charge separation/transport, increasing further the J sc and the fill factor. The ionic gating concept demonstrated here for most simple classical planar small-molecule OPV cells can be potentially applied to more complex highly efficient hybrid devices, such as perovskite photovoltaic with an ETL or a hole transport layer, providing a new way to tune their properties via controllable and reversible interfacial doping of charge collectors and transport layers.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Saranin

Mahmoodpoor

Voroshilov

et al. 2021

ACS Appl. Mater. Interfaces

Self Cite

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“…However, at higher Vbias of 2V, the internal E-field in PCBM most probably pulls MA + ions further into the PCBM layer. Also this is a hypothesis at this stage (not yet confirmed by direct measurement of ions present in ETL) for explaining EL improvement dynamics, we believe that this ETL doping is highly preferable by porous structure of fulleride (C60 and PCBM) molecular solids This type of penetration of ions into PCBM [23] and into C60 ETLs was demonstrated in [23][24][25][26][27][28] by external ionic gating in ionic liquids. The MA+ ions coming from PS have smaller size as compared to large ions of ionic liquids, and they can easily penetrate into PCBM, once there is a driving force for this.…”

Section: Resultsmentioning

confidence: 91%

Mixed halide perovskite light emitting solar cell

Gets

Ishteev

Liashenko

et al. 2018

J. Phys.: Conf. Ser.

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Organic-inorganic halide perovskites recently have emerged as a promising material for highly effective light-emitting diodes (LEDs) and solar cells (SCs). Despite efficiencies of both perovskite SCs and LEDs are already among the best, the development of a perovskite dual functional device that is capable of working in these two regimes with high efficiencies is still challenging. Here we demonstrate that the dual functional device based on mixed halide perovskite CH3NH3PbBr2I can be switched from SC to LED with low threshold voltage Vth < 2 V by exposing to Sun at open circuit Voc or at small bias voltage of Vpol ~ 1 -2 V. Such photo-poling creates in-situ p-i-n junction via methylammonium (CH3NH3 + , MA + ) and I -/Brions migration to interfaces, lowering charge injection barriers, and self-balancing injection currents in perovskite LED. We show that before the photo-poling, the electroluminescence (EL) is highly unstable in LED regime, whereas after the photo-poling, stabilized EL exhibits unusual dynamics, increasing with time and poling cycle number, while Vth and injection current decrease with cycling runs.Additionally, photo-induced and current-induced halide segregation accumulates with cycling, that is found beneficial for LED, increasing its efficiency and brightness, but reversibly degrading photovoltaic (PV) performance, which can be easily recovered.

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“…This requires new architecture, which combines IL supercapacitor, connected in parallel with OPV as we introduced earlier for a polymeric OPV with IL, 25 and demonstrated its advantages in tandems. 27 In this paper, we apply the gating in IL to classical small molecule OPV with DEME−BF 4 IL and study the dynamics of this ionically gated system of MWCNT@Fullerene (i.e. cathode@ETL) to understand how it accumulates electrons, and how the ions move first in MWCNT network and then into and through fullerene molecular ETL layer of different thicknesses.…”

Section: Introductionmentioning

confidence: 99%

Ionically Gated Small Molecule OPV: Interfacial doping of Charge collector and Transport layer

Saranin¹,

Mahmoodpoor²,

Voroshilov³

et al. 2018

Preprint

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We demonstrate the controlled n-doping in small molecule organic photovoltaic (OPV) systems by ionic gating of multi-wall carbon nanotube (MWCNT) coated fullerenes: C 60 and C 70 . Such electric double layer charging (EDLC) doping, achieved by ionic liquid (IL) charging, allows tuning the electronic concentration in the acceptor layers, increasing it by orders of magnitude. This leads to decreasing both the series and shunt resistances of OPV and allows to use thick (up to 200 nm) electron transport layers, increasing the durability and stability of OPV. Two stages of OPV enhancement are described, upon increase of gating bias: at small (or even zero) V g the interface between 1 porous transparent MWCNT charge collector with fullerene is improved, becoming an ohmic contact. This changes the S-shaped I-V curve and improves the electrons collection by a MWCNT turning it into a good cathode. The effect further enhances at higher V g due to raising of Fermi level and lowering of MWCNT work function. At next qualitative stage, the acceptor layer becomes n-doped by electron injection from MWCNT and ions penetration into fullerene. At this step the internal built-in field is created within OPV, that helps exciton dissociation and charge separation/transport, increasing further the I sc and the F F (Filling factor). Overall power conversion efficiency (PCE) increases nearly 50 times in classical CuPc/fullerene OPV with bulk heterojunction photoactive layer and MWCNT cathode. Ionic gating of MWCNTfullerene part of OPV opens a new way to tune the properties of organic devices, based on controllable and reversible doping and modulation of work function.

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Tunable organic PV parallel tandem with ionic gating

Cited by 8 publications

References 39 publications

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Mixed halide perovskite light emitting solar cell

Ionically Gated Small Molecule OPV: Interfacial doping of Charge collector and Transport layer

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