Quantifying the effect of energetic disorder on organic solar cell energy loss

Khan, Saeed‐Uz‐Zaman; Bertrandie, Jules; Gui, Manting; Sharma, Anirudh; Alsufyani, Wejdan; Gorenflot, Julien; Laquai, Frédéric; Baran, Derya; Rand, Barry P.

doi:10.1016/j.joule.2022.10.012

Cited by 20 publications

(16 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This Gaussian width is represented by the fit parameter λ RO , which in principle represents the reorganization energy corresponding to the CT state to ground state transition, while in reality it also includes the energetic disorder, if not specifically accounted for. [ 32–35 ] In that case, the average E CT would be higher than E g A , but the higher energy CT‐states transfer to the acceptor and thus are not visible in EL spectroscopy. Second, the interface state and the acceptor exciton being isoenergetic, hybridize: [ 30,37–40 ] the interface (CT) state thus becomes a CT‐LE A hybrid state, with the local acceptor component LE A potentially becoming predominant as the CT state energy (without hybridization) increases and thus, the hybrid state emission becomes virtually similar to that of the acceptor's local excitonic state.…”

Section: Resultsmentioning

confidence: 99%

Increasing the Ionization Energy Offset to Increase the Quantum Efficiency in Non‐Fullerene Acceptor‐Based Organic Solar Cells: How Far Can We Go?

Gorenflot

Alsufyani

Alqurashi

et al. 2023

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

more than 30 years of empirical optimization [1,2] from the first proof of concept by Tang delivering only 1% power conversion efficiency (PCE) in 1986, [3] to develop the latest Y-series of non-fullerene acceptor (NFA) molecules [4,5] that now yield efficiencies close to 20%. [6][7][8][9][10][11] The field of OPV has always been in need of design principles that could guide the synthesis of new molecules. In parallel to molecular engineering, our understanding of the photophysics governing the solar cell performances has considerably increased in the last 30 years, and such sets of meaningful design rules have started to solidify. [12][13][14][15] Furthermore, first principlebased computational materials chemistry has progressed to the point where energy levels can not only be computed in the gas phase, but also extrapolated to films, which allows for screening many potential structures of OPV materials and selecting the most promising for synthesis. [14] For low-bandgap NFA-based solar cells, we previously showed that the acceptor's ionization energy has to be ≈0.45 eV higher (more negative with respect to vacuum) than that of the donor, to maximize exciton quenching by hole transfer from the acceptor to the donor and in turn the solar cells' internal quantum efficiency (IQE). [12,14] We showed that this hole transfer efficiency sets a ceiling to the solar cells' IQE. The 0.45 eV ionization energy offset ΔIE was shown to be required to counterbalance energy level bending (measured as bias potential B) at the donor-acceptor (D/A) interface, which increases the energy of the interfacial charge transfer (CT) and thus impedes the exciton-to-CT-state transition if ΔIE is low. [12,14,16] The interfacial energy level bending is a consequence of the energetic landscape in NFA-based blends, more specifically the interaction of charges with the surrounding molecules' (NFA and donors) intrinsic quadrupole moments. [12,14,15,17,18] On the other hand, the bending facilitates charge separation (CT to free charge conversion) and diffusion from the interface, explaining the observation of barrier-less charge generation in the top-performing OPV systems. [19] Very recently, we reported that the same applies to ternary blends, composed of one donor and two acceptors. [20] Interestingly, the IQE follows the average IE of both acceptors weighted by their blending (weight) ratio. [20] While Molecular engineering of organic semiconductors provides a virtually unlimited number of possible structures, yet only a handful of combinations lead to state-of-the-art efficiencies in photovoltaic applications. Thus, design rules that guide material development are needed. One such design principle is that in a bulk heterojunction consisting of an electron donor and lower bandgap acceptor an offset (ΔIE) of at least 0.45 eV is required between both materials ionization energies to overcome energy level bending at the donor-acceptor interface, in turn maximizing the charge separation yield and the cell's internal quantum efficiency. The present...

show abstract

Section: Resultsmentioning

confidence: 99%

Increasing the Ionization Energy Offset to Increase the Quantum Efficiency in Non‐Fullerene Acceptor‐Based Organic Solar Cells: How Far Can We Go?

Gorenflot

Alsufyani

Alqurashi

et al. 2023

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

show abstract

“…Generally, the energy level offset between the HOMO and LUMO determines the dissociation of photoexcited charges at the D–A interface. However, since the not very discreet energy levels 44 and the existence of energetic disorder, 45 it is difficult to predict the energetic landscape. To understand the charge transfer between the donor and acceptors, photoluminescence (PL) spectra were performed.…”

Section: Resultsmentioning

confidence: 99%

Simultaneously enhancing the photovoltaic parameters of ternary organic solar cells by incorporating a fused ring electron acceptor

et al. 2023

View full text Add to dashboard Cite

show abstract

“…By contrast, the EL emission of PTQ12:Y12 is completely dominated by Y12 S 1 emission, leading to a much lower ΔV oc,nrad of 0.21 V (Table S7 and Figure S16), in agreement with previous demonstrations of low nonradiative voltage losses when S 1 and CT-state emission is strongly mixed. 36,37 Such a low ΔV oc,nrad compares extremely favorably with other high-efficiency organic solar cells, using either chlorinated or nonchlorinated solvents, 38 and suggests that high-quality donor−acceptor interfaces with low CT-state energetic disorder 39,40 can be achieved using green solvents such as 2MeTHF. We note that achieving such a low ΔV oc,nrad is particularly promising given the unique combination of green solvent and synthetically simple polymer that we used here.…”

mentioning

confidence: 89%

Biorenewable Solvents for High-Performance Organic Solar Cells

et al. 2023

View full text Add to dashboard Cite

With the advent of nonfullerene acceptors (NFAs), organic photovoltaic (OPV) devices are now achieving high enough power conversion efficiencies (PCEs) for commercialization. However, these high performances rely on active layers processed from petroleum-based and toxic solvents, which are undesirable for mass manufacturing. Here, we demonstrate the use of biorenewable 2-methyltetrahydrofuran (2MeTHF) and cyclopentyl methyl ether (CPME) solvents to process donor: NFA-based OPVs with no additional additives in the active layer. Furthermore, to reduce the overall carbon footprint of the manufacturing cycle of the OPVs, we use polymeric donors that require a few synthetic steps for their synthesis, namely, PTQ10 and FO6-T, which are blended with the Y-series NFA Y12. High performance was achieved using 2MeTHF as the processing solvent, reaching PCEs of 14.5% and 11.4% for PTQ10:Y12 and FO6-T:Y12 blends, respectively. This work demonstrates the potential of using biorenewable solvents without additives for the processing of OPV active layers, opening the door to large-scale and green manufacturing of organic solar cells.

show abstract

Quantifying the effect of energetic disorder on organic solar cell energy loss

Cited by 20 publications

References 48 publications

Increasing the Ionization Energy Offset to Increase the Quantum Efficiency in Non‐Fullerene Acceptor‐Based Organic Solar Cells: How Far Can We Go?

Increasing the Ionization Energy Offset to Increase the Quantum Efficiency in Non‐Fullerene Acceptor‐Based Organic Solar Cells: How Far Can We Go?

Simultaneously enhancing the photovoltaic parameters of ternary organic solar cells by incorporating a fused ring electron acceptor

Biorenewable Solvents for High-Performance Organic Solar Cells

Contact Info

Product

Resources

About