Revealing optically induced dipole-dipole interaction effects on charge dissociation at donor:acceptor interfaces in organic solar cells under device-operating condition

Hsiao, Yu-Che; Wu, Ting; Li, Mingxing; Qin, Wei; Yu, Luping; Hu, Bin

doi:10.1016/j.nanoen.2016.06.015

Cited by 18 publications

(13 citation statements)

References 53 publications

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“…However, V oc difference is negligible for these two devices therefore, it is expected that the interface is somehow similar. Moreover, it has been recently shown by us that at V oc condition, when the built‐in field is balanced by an applied field, the optically generated dipoles become randomly oriented in the amorphous PTB7 transport layer, diminishing the dipole effects on photovoltaic actions . Therefore, at V oc condition under illumination, photogenerated dipoles in PTB7 layer are random and similar V oc is expected for both devices.…”

Section: Resultsmentioning

confidence: 78%

Effect of Photogenerated Dipoles in the Hole Transport Layer on Photovoltaic Performance of Organic–Inorganic Perovskite Solar Cells

Ahmadi

Hsiao

et al. 2016

Advanced Energy Materials

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to the electronic and morphological parameters in the active perovskite layer, the electron transport layer (ETL) and hole transport layer (HTL) are significantly important in determining the photovoltaic performance in perovskite solar cells. [3][4][5][6] Specifically, the role of a transport layer in solar cells is to facilitate charge transport and assist charge collection toward the respective electrodes as well as inhibiting from recombination of charge carriers on the path to the electrodes. [3] Meanwhile, the open circuit voltage (V oc ) is normally determined by the energy differences between the Fermi levels of the ETL and the HTL. There are certain prerequisites for a hole transport material in order to perform more efficiently in perovskite solar cells, such as energy band alignment, suitable hole mobility, chemical compatibility with the perovskite layer as well as good thermal and photochemical stability. [5,6] In addition, morphology and crystallinity of this layer plays an important role. The importance and influence of these parameters in the transport layer on perovskite solar cells performance have been extensively investigated. [3,[5][6][7][8][9][10] In this article, we demonstrate the importance of photogenerated dipoles in the HTL as a new strategy to improve the photovoltaic performance of planar perovskite solar cells. In order to explore this effect, we select two HTLs with similar conjugated thiophene backbones, namely PTB7 and P3HT with significant and negligible optically generated dipoles. Moreover, our measurements based on space charge limited current model indicate that PTB7 and P3HT have hole mobilities in the same order in agreement with previous publications (Figure S1, Supporting Information). [11][12][13][14] It has been shown that PTB7 has a relatively large internal dipoles through intrachain charge transfer from benzodithiophene to thienothiophene moieties under photoexcitation. [15] The dipole moments (D) in ground and excite states have been measured to be 3.76 and 7.13 for PTB7 and 0.19 and 0.43 for P3HT, respectively. [15] In general, perovskites have the advantage of both bulk polarization and semiconducting properties. [16][17][18][19][20] It was shown that the presence of a polar molecule, methylammonium at the center of perovskite introduces the possibility of orientational P3HT-poly(3-hexylthiophene) are separately used as the HTL with significant and negligible photoinduced dipoles, respectively. Electric field-induced photoluminescence quenching provides the first-hand evidence to indicate that the photoinduced dipoles are partially aligned in the amorphous PTB7 layer under the influence of device built-in field. By monitoring the recombination process through magneto-photocurrent measurements under device operation condition, it is shown that the photoinduced dipoles in PTB7 layer can decrease the recombination of photogenerated carriers in the active layer in perovskite solar cells. Furthermore, the capacitance measurements suggest that the photoinduced dipoles ...

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Section: Resultsmentioning

confidence: 78%

Effect of Photogenerated Dipoles in the Hole Transport Layer on Photovoltaic Performance of Organic–Inorganic Perovskite Solar Cells

Ahmadi

Hsiao

et al. 2016

Advanced Energy Materials

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“…Our early studies have shown that magneto-J sc can be used as a method in situ to dynamically monitor the dissociation at D:A interfaces in organic solar cells under device operation. [41][42][43][44][45] Normally, magneto-J sc can be established by gradually increasing the magnetic field while monitoring photocurrent J sc . Essentially, using magneto-J sc to monitor the charge separation at D:A interfaces is based on following three subsequent processes.…”

Section: Context and Scalementioning

confidence: 99%

Self-Stimulated Dissociation in Non-Fullerene Organic Bulk-Heterojunction Solar Cells

Zhu

Zhang

et al. 2020

Joule

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“…We know that polaron pairs can be largely formed towards light-emitting excitons in OLEDs under electrical injection 32, 33 . It has been experimentally observed that an external magnetic field can conveniently change the populations on the singlet and triplet polaron pairs, leading to magneto-EL 18, 34, 35 and magneto-current 36, 37 due to largely different recombination rates associated with singlets and triplets. Therefore, magneto-EL can be measured at two different conditions: constant-current and constant-voltage modes, while monitoring the EL intensity with scanning magnetic field 18, 19, 38 .…”

Section: Resultsmentioning

confidence: 99%

Investigating underlying mechanism in spectral narrowing phenomenon induced by microcavity in organic light emitting diodes

et al. 2019

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This paper reports our experimental studies on the underlying mechanism responsible for electroluminescence spectral narrowing phenomenon in the cavity-based organic light-emitting diodes. It is found that the microcavity generates an emerging phenomenon: a magneto-photoluminescence signal in Poly(9,9-dioctylfluorene-alt-benzothiadiazole) polymer under photoexcitation, which is completely absent when microcavity is not used. This provides an evidence that microcavity leads to the formation of spatially extended states, functioning as the intermediate states prior to the formation of Frenkel excitons in organic materials. This is confirmed by the magneto-electroluminescence solely observed from the cavity-based light-emitting diodes under electrical injection. Furthermore, the narrowed electroluminescence output shows a linear polarization, concurrently occurred with magneto-electroluminescence. This indicates that the spatially extended sates become aligned towards forming coherent light-emitting excitons within the microcavity through optical resonance. Clearly, the spatially extended states present the necessary condition to realize electroluminescence spectral narrowing phenomenon towards lasing actions in cavity-based organic light-emitting diodes.

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Revealing optically induced dipole-dipole interaction effects on charge dissociation at donor:acceptor interfaces in organic solar cells under device-operating condition

Cited by 18 publications

References 53 publications

Effect of Photogenerated Dipoles in the Hole Transport Layer on Photovoltaic Performance of Organic–Inorganic Perovskite Solar Cells

Effect of Photogenerated Dipoles in the Hole Transport Layer on Photovoltaic Performance of Organic–Inorganic Perovskite Solar Cells

Self-Stimulated Dissociation in Non-Fullerene Organic Bulk-Heterojunction Solar Cells

Investigating underlying mechanism in spectral narrowing phenomenon induced by microcavity in organic light emitting diodes

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