Promising long-term stability of encapsulated ITO-free bulk-heterojunction organic solar cells under different aging conditions

Sapkota, Subarna B.; Spies, Annika; Zimmermann, Birger; Dürr, I.; Würfel, Uli

doi:10.1016/j.solmat.2014.07.004

Cited by 61 publications

(51 citation statements)

References 55 publications

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“…[1,2] Additionally, promising long-term stability has been demonstrated, [3][4][5] a short energy payback time can be expected [6,7] and as an exemplary large scale application they were incorporated in the roof top of the German pavilion at the Expo 2015. [8] These advances have been enabled by more sophisticated chemical synthesis of donor and acceptor materials with higher absorption coefficients and beneficial bandgap engineering as well as the establishment of new interfacial compounds that increase the selectivity of the contacts.…”

Section: Introductionmentioning

confidence: 99%

On the Impact of Contact Selectivity and Charge Transport on the Open‐Circuit Voltage of Organic Solar Cells

Spies

List

Sarkar

et al. 2016

Advanced Energy Materials

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However, in comparison to established inorganic-based photovoltaic technologies organic solar cells possess still a much lower efficiency. [2,[9][10][11][12] The efficiency η of solar cells is determined bywhere J SC is the short-circuit current density, V OC is the open-circuit voltage, FF is the fill factor, and P in is the incident power density. The relatively poor transport properties (low mobilities) of the disordered organic materials [13,14] applied in OSC lead to a strong accumulation of charge carriers under current flow and thus to an increase in nongeminate recombination. [10] Consequently, the FF is reduced and for cases of extremely low charge carrier mobilities also J SC , which results in a low overall power conversion efficiency. [10,11,15] Further, due to the relatively low permittivity of the organic materials a significant fraction of the absorbed photon energy is required as driving force for the exciton dissociation of the coulombic bound electron-hole pair (offset between the lowest unoccupied molecular orbitals of donor and acceptor) which lowers the achievable power conversion efficiency significantly. [9] In addition to the latter, a key loss mechanism originates from additional nonradiative recombination pathways. Besides the nongeminate recombination via trap states as a first order recombination process, the recombination at the electrodes, i.e., surface recombination, is an additional loss channel. Surface recombination in OSC was investigated intensively in different perspectives which indicates the importance of a thorough understanding of the underlying mechanisms. [16][17][18][19][20] Kirchartz et al. derived the ideality factor differentially by the light intensity dependence of the open-circuit voltage and demonstrated that the presence of surface recombination leads to the occurrence of an ideality factor n id < 1. [18] But also the charge carrier mobility µ dependent efficiency of OSC has been investigated in terms of surface recombination. It seems to be counterintuitive to assume that the device efficiency is maximum at a finite optimum mobility. Yet, this case is in detail discussed by Deibel et al. and Kirchartz et al., who showed that an optimum mobility exists in the presence of not ideally selective contacts and that faster kinetics by mobilities higher than the optimum will result in a reduction of the overall efficiency. [21,22] TressThe selectivity of electrodes of solar cells is a critical factor that can limit the overall efficiency. If the selectivity of an electrode is not sufficient both electrons and holes recombine at its surface. In materials with poor transport properties such as in organic solar cells, these surface recombination currents are accompanied by large gradients of the quasi-Fermi energies as the driving force. Experimental results from current-voltage characteristics, advanced photo-and electroluminescence as well as charge extraction of three different photoactive materials are shown and compared to drift-diffusion simulations. It can be conc...

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Section: Introductionmentioning

confidence: 99%

On the Impact of Contact Selectivity and Charge Transport on the Open‐Circuit Voltage of Organic Solar Cells

Spies

List

Sarkar

et al. 2016

Advanced Energy Materials

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“…However, the lifetime of OPVs is a key factor hindering commercialization [4,5]. Although the lifetime of poly(3-hexylthiophene) (P3HT) : phenyl-C61-butyric acid methyl ester (PCBM) devices can be up to 1000 hours [6], this still represents significantly worse performance than, for example, inorganic silicon photovoltaics, which have a lifetime approaching 25 years [7].…”

Section: Introductionmentioning

confidence: 99%

“…The rate of degradation due to water increases with relative humidity (RH) [16]. Deterioration in performance can also result from changes in the bulk heterojunction (BHJ) morphology [5]. For example, several studies have showed that BHJ materials aggregate over time, thereby reducing exciton dissociation and hence short circuit current [2,17].…”

Section: Introductionmentioning

confidence: 99%

Enhanced lifetime of organic photovoltaic diodes utilizing a ternary blend including an insulating polymer

Al-Busaidi

Pearson

Groves

et al. 2017

Solar Energy Materials and Solar Cells

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“…Polymer solar cells (PSCs) have drawn great attention owing to their key advantages of synthetic variability, light weight, low cost, large-area roll to roll fabrication and the lucrative possibility of integration directly into flexible devices [1][2][3][4][5][6]. Power conversion efficiency (PCE) of PSCs has been over efficiencies of 9% with good ambient stability for single cell devices [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Application of a water-soluble metallophthalocyanine derivative as a cathode interlayer for the polymer solar cells

Jia

Han

Zhou

et al. 2015

Solar Energy Materials and Solar Cells

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Promising long-term stability of encapsulated ITO-free bulk-heterojunction organic solar cells under different aging conditions

Cited by 61 publications

References 55 publications

On the Impact of Contact Selectivity and Charge Transport on the Open‐Circuit Voltage of Organic Solar Cells

On the Impact of Contact Selectivity and Charge Transport on the Open‐Circuit Voltage of Organic Solar Cells

Enhanced lifetime of organic photovoltaic diodes utilizing a ternary blend including an insulating polymer

Application of a water-soluble metallophthalocyanine derivative as a cathode interlayer for the polymer solar cells

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