N-dopants optimize the utilization of spontaneously formed photocharges in organic solar cells

Abstract

The non-fullerene acceptor (NFA) not only brings rapid efficiency progress to organic solar cell (OSC), but also arouses scientific interest in re-evaluating the photocharge generation route via spontaneous or heterojunction-assisted...

Solid Solvation Assisted Electrical Doping Conserves High‐Performance in 500 nm Active Layer Organic Solar Cells

“…By using the developed methods, the L dr and L diff are correspondingly related to the figures of merit (FoM) 𝜃 and 𝛼 (see calculating details in ESI, and see experimental results in Figure S9 and S10, and Table S10, Supporting Information). [15,16] The two FoMs are designed to estimate the competition between the photocharge collection and recombination at short-circuit and open-circuit conditions. [46] According to their simple relationships with the BHJ film thickness (d), the L dr and L diff can be obtained by d/𝜃 1/2 and d/(2𝛼) 1/2 .…”

“…Theoretically, the electrical doping can facilitate exciton splitting at the donor/acceptor heterojunction and in neat non-fullerene acceptor (NFA) by tuning the energy landscape. [13][14][15][16] The doping induced charge density increment may also modify the charge carrier profile within BHJ film and the corresponding internal electric field. [17][18][19] Though the electrical doping seems like a rational solution to the problems in thick film OSCs, the unexpected useless function on PCE improvement hinders its practical application.…”

Sequentially N‐Doped Acceptor Primer Layer Facilitates Electron Collection of Inverted Non‐Fullerene Organic Solar Cells

“…[37] The doping process between N-DMBI and Y6 is accomplished by the thermally-activated hydride transfer from the intermediate N-DMBI• radicals. [37] Because of the sufficiently low singly occupied molecular orbital (SOMO) energy level of N-DMBI• (−2.23 eV), in some instances, the doping reaction can proceed without energy offset between the highest occupied molecular orbital (HOMO) level of N-DMBI dopant and the lowest unoccupied molecular orbital (LUMO) level of the host material. [38,39] As another Y-series acceptor developed from Y6, L8-BO molecules only differ in their branched alkyl chains, endowing them better molecular packing but similar physicochemical properties.…”

“…[40] Hence, we assume that the electron donation from N-DMBI to L8-BO is also initiated by N-DMBI• radicals, transforming [L8-BO]+[N-DMBI•] to [L8-BO − /N-DMBI + ] complex via an intermediate step of hydrogen removal (Figure 1c). [37,38] Correspondingly, we measured the hydrogen nuclear magnetic resonance ( 1 H-NMR) spectra for neat L8-BO/N-DMBI and L8-BO:N-DMBI mixtures to confirm the production of N-DMBI + . [41] As shown in Figure 1d, the absence of the imidazole core hydrogen of N-DMBI molecules mixed with L8-BO validates this doping reaction.…”

Selective Chemical Reactivity of Non‐Fullerene Acceptor for Photoelectrochemical Bioassay of Urease Activity

“…[23][24][25][26][27] The well-known fullerene derivatives (PC 61 BM and PC 71 BM) have high electron mobility and excellent electron-withdrawing ability, which were widely employed as the n-type materials. [28][29][30][31] However, despite these excellent characteristics, fullerene-based n-type materials have serious flaws, such as limited energy-level tunability, poor light-absorption properties, and photochemical instability. [32][33][34] Compared with fullerenes, non-fullerene acceptors (NFAs) have wide absorption in the visible to near-infrared wavelength range, remarkably enhancing the light-harvesting ability.…”