Mobility Guidelines for High Fill Factor Solution‐Processed Small Molecule Solar Cells

Proctor, Christopher M.; Love, John A.; Nguyen, Thuc‐Quyen

doi:10.1002/adma.201401725

Cited by 200 publications

(227 citation statements)

References 45 publications

(92 reference statements)

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“…[24] Therefore, we can conclude that the moderate FF around 0.6 in this work is partially due to the low mobilities of the blends. [53] The measured mobilities of the PBDT-TPD:PNDI-T and PBDT-TPD:PC 71 BM solar cells are also in good agreement with the previous reports in literature. [29,54] …”

Section: Space Charge Limited Current Charge (Sclc) Mobilitysupporting

confidence: 80%

8.0% Efficient All‐Polymer Solar Cells with High Photovoltage of 1.1 V and Internal Quantum Efficiency near Unity

Zhang

et al. 2017

Advanced Energy Materials

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In very recent years, growing efforts have been devoted to the development of all‐polymer solar cells (all‐PSCs). One of the advantages of all‐PSCs over the fullerene‐based PSCs is the versatile design of both donor and acceptor polymers which allows the optimization of energy levels to maximize the open‐circuit voltage (Voc). However, there is no successful example of all‐PSCs with both high Voc over 1 V and high power conversion efficiency (PCE) up to 8% reported so far. In this work, a combination of a donor polymer poly[4,8‐bis(5‐(2‐octylthio)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(5‐(2‐ethylhexyl)‐4H‐thieno[3,4‐c]pyrrole‐4,6(5H)‐dione)‐1,3‐diyl] (PBDTS‐TPD) with a low‐lying highest occupied molecular orbital level and an acceptor polymer poly[[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐thiophene‐2,5‐diyl] (PNDI‐T) with a high‐lying lowest unoccupied molecular orbital level is used, realizing high‐performance all‐PSCs with simultaneously high Voc of 1.1 V and high PCE of 8.0%, and surpassing the performance of the corresponding PC71BM‐based PSCs. The PBDTS‐TPD:PNDI‐T all‐PSCs achieve a maximum internal quantum efficiency of 95% at 450 nm, which reveals that almost all the absorbed photons can be converted into free charges and collected by electrodes. This work demonstrates the advantages of all‐PSCs by incorporating proper donor and acceptor polymers to boost both Voc and PCEs.

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Section: Space Charge Limited Current Charge (Sclc) Mobilitysupporting

confidence: 80%

8.0% Efficient All‐Polymer Solar Cells with High Photovoltage of 1.1 V and Internal Quantum Efficiency near Unity

Zhang

et al. 2017

Advanced Energy Materials

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“…For example, the µ e / µ h ratios dropped from around 10 to about 0.82 for BIT4FSe:PC 71 BM and from 4.5 to 1.4 for BIT4FTh:PC 71 BM before and after CH 2 Cl 2 vapor annealing, respectively. Therefore, CH 2 Cl 2 vapor annealing resulted in a much enhanced µ h together with a considerably better balanced hole and electron mobility, which led to a much higher charge-carrier extraction [91][92][93][94][95] In order to test the possible use of these devices in practical applications, the device shelf lifetimes (storage stability) were tested in air after simple encapsulation. As shown in Figure 5 , the devices retained over 90% of their initial PCE after about 150 h (the results from 8 individual cells of each type of smallmolecules device and treatment conditions were averaged).…”

Section: Resultsmentioning

confidence: 99%

Difluorobenzothiadiazole‐Based Small‐Molecule Organic Solar Cells with 8.7% Efficiency by Tuning of π‐Conjugated Spacers and Solvent Vapor Annealing

Wang

Xiao

Yan

et al. 2016

Adv Funct Materials

101

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The synthesis of a series of tetrafl uorine-substituted, wide-bandgap, small molecules consisting of various π-conjugated spacers (furan, thiophene, selenophene) between indacenodithiophene as the electron-donating core and the electron-defi cient difl uorobenzothiadiazole unit is reported and the effect of the π-conjugated spacers on the photovoltaic properties is investigated. The alteration of the π-conjugated spacer enables fi ne-tuning of the photophysical properties and energy levels of the small molecules, and allows the adjustment of the charge-transport properties, the morphology of the photoactive fi lms, as well as their photovoltaic properties. Moreover, most of these devices exhibit superior device performances after CH 2 Cl 2 solvent annealing than without annealing, with a high fi ll factor (0.70-0.75 for all cases). Notably, the devices based on the new molecule BIT4FTh (with thiophene as the spacer) show an outstanding PCE of 8.7% (with an impressive FF of 0.75), considering its wide-bandgap (1.81 eV), which is among the highest effi ciencies reported so far for small-molecules-based solar cells. The morphologies of the photoactive layers with/without CH 2 Cl 2 solvent annealing are characterized by atomic force microscopy, transmission electron microscopy and two-dimensional grazing incidence X-ray diffraction analysis. The results reported here clearly indicate that highly effi cient small-molecules-based solar cells can be achieved through rational design of their molecular structure and optimization of the phaseseparated morphology via an adapted solvent-vapor annealing process.

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“…In addition, simulation [5,6] and experimental [13][14][15] works show that charge transport have effect on PCE of OSCs and a detailed analysis of bulk heterojunction organic solar cells reveals that low V oc is the main factor limiting this efficiency [9]. This implies that the V oc of an OSC depends on the transport properties of the charge carrier in the material, which has not yet been studied adequately.…”

Section: Introductionmentioning

confidence: 99%

Charge-carrier-mobility-dependent-open-circuit-voltage-in-organic-and-hybrid-solar-cells

Ompong¹,

Singh²

2016

Front Nanosci Nanotech

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A better understanding of the open-circuit voltage (V oc ) related losses in organic solar cells (OSCs) is desirable in order to assess their photovoltaic performance. We have derived V oc as a function of charge carrier mobilities ( e µ and h µ ) for organic and hybrid solar cells by optimizing the drift-diffusion current density. The V oc thus obtained depends on the energy difference between the highest occupied molecular orbital (HOMO) level and the quasi-Fermi level of holes of the donor material and on the ratio of the electron ( e µ ) and hole ( h µ ) mobilities in the blend. It is found that the V oc increases with the increase of the mobility ratio h e µ µ / . The most loss in V oc is contributed by the energetics of the donor and acceptor materials.

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Mobility Guidelines for High Fill Factor Solution‐Processed Small Molecule Solar Cells

Cited by 200 publications

References 45 publications

8.0% Efficient All‐Polymer Solar Cells with High Photovoltage of 1.1 V and Internal Quantum Efficiency near Unity

8.0% Efficient All‐Polymer Solar Cells with High Photovoltage of 1.1 V and Internal Quantum Efficiency near Unity

Difluorobenzothiadiazole‐Based Small‐Molecule Organic Solar Cells with 8.7% Efficiency by Tuning of π‐Conjugated Spacers and Solvent Vapor Annealing

Charge-carrier-mobility-dependent-open-circuit-voltage-in-organic-and-hybrid-solar-cells

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