Photochemical Transformation of Fullerenes

Wang, Jia; Enevold, Jenny; Edman, Ludvig

doi:10.1002/adfm.201203386

Cited by 39 publications

(43 citation statements)

References 41 publications

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“…A possible explanation for this synergy is that fullerene oligomerization reactions are strongly concentration-dependent and not directly proportional to light intensity due to a partial of back-reaction from excited triplet states. 45 An enhancement of WBC device stability after light treatment could indicate a higher PC 60 BM concentration available for oligomerization thereby restricting the degradation of performance. However, UV-vis data ( Figure S2) confirm that the average PCDTBT and PC 60 BM composition remains similar regardless of solution casting technique.…”

Section: Resultsmentioning

confidence: 99%

Synergetic enhancement of organic solar cell thermal stability by wire bar coating and light processing

Tan

Wong

et al. 2015

J. Mater. Chem. C

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† Electronic Supplementary Information (ESI) available: SC and WBC drying kinetics measurements. UV-vis absorption spectra of SC and WBC PCDTBT:PC60BM blend layers. PL spectra of SC and WBC blended layers and their respective PCDTBT neat layers. EQE of blend devices deposited by SC and WBC techniques. Optical microscopy images of the blend layer deposited by SC and WBC on SiOx (as cast) and PEDOT:PSS (at 80°C and 140°C thermal annealing temperature). SeeWe demonstrate that organic solar cells can exhibit different morphological and performance stability under thermal stress depending upon the processing technique employed, without compromising initial device efficiency. In particular, we investigate benchmark PCDTBT:PC60BM solar cells fabricated by wire bar coating (a technique attractive for commercial manufacture) and the more widely employed, lab scale, technique of spin coating. For this system, wire bar deposition results in superior device stability, with lifetime improvements in excess of 20-fold compared to spun cast devices. Neutron reflectivity reveals that the enhanced PC60BM segregation to the top interface in the slower, wire bar, casting process is likely responsible for the hindered PC60BM nucleation at tens of nm length scale, characterized by atomic force microscopy (AFM), and thus enhanced morphological stability. Modest light exposure of the active layer (at approximately 10 mWcm -2 ), known to reversibly photo-oligomerize fullerenes and thus impart morphological stability, is found to further improve device stability by a factor of 10. The combined effects of wire bar coating and light processing are highly synergetic, resulting in solar cells which are overall 200 times more stable than devices prepared by spin casting without light processing.

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Section: Resultsmentioning

confidence: 99%

Synergetic enhancement of organic solar cell thermal stability by wire bar coating and light processing

Tan

Wong

et al. 2015

J. Mater. Chem. C

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“…Previous studies have suggested that light exposure of C 60 and PC 60 BM films can result in fullerene oligomerization, thereby substantially reducing their solubility 18,26 . Such fullerene oligomerization is therefore the most probable origin of the enhanced morphological stability of PCDTBT:PC 60 BM blend films following light exposure reported above.…”

Section: Resultsmentioning

confidence: 99%

Performance enhancement of fullerene-based solar cells by light processing

et al. 2013

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A key challenge to the commercialization of organic bulk heterojunction solar cells is the achievement of morphological stability, particularly under thermal stress conditions. Here we show that a low-level light exposure processing step during fabrication of blend polymer:PC 60 BM solar cells can result in a 10-fold increase in device thermal stability and, under certain conditions, enhanced device performance. The enhanced stability is linked to the light-induced oligomerization of PC 60 BM that effectively hinders their diffusion and crystallization in the blend. We thus suggest that light processing may be a promising, general and cost-effective strategy to optimize fullerene-based solar cell performance. The low level of light exposure required suggests not only that this may be an easily implementable strategy to enhance performance, but also that light-induced PC 60 BM oligomerization may have inadvertently influenced previous studies of organic solar cell device behaviour.

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“…[43][44][45] The Nyquist plots weremeasured under 1sun illuminationwith an applied bias voltage of 0.8 Vint he frequency range from 2MHz to 0.5 Hz. [39,47] In the presentc ase, the device without t-BAI doping exhibits as lope of 1.87 kT/q, [48,49] indicating as trong energy loss owing to trap-assisted recombination. In the plots, the low-frequency one relatest ot he recombination resistance (R rec )a tt he interface of the perovskite/charget ransport layer (CTL), the high-frequency one concerns the charge-transfer resistance( R ct )f rom perovskite to CTL, and R s is the sheet resistance of the conductive electrode.…”

Section: Resultsmentioning

confidence: 57%

Fabrication of Efficient and Stable Perovskite Solar Cells in High‐Humidity Environment through Trace‐Doping of Large‐Sized Cations

Liu

Wang

et al. 2019

ChemSusChem

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Solution‐processed organic–inorganic lead halide perovskites have shown photovoltaic performance above 23 %, attracting great attention. However, the champion devices require fabrication in a controlled inert/dry atmosphere. The development of highly efficient and stable perovskite solar cells under high‐humidity atmosphere conditions for future commercialization is still challenging, especially for CH3NH3PbI3 (MAPbI3), which is vulnerable to moisture. In this study, a large‐sized tert‐butylammonium [C(CH3)3NH3+] organic cation was incorporated into the MAPbI3 crystalline structure, which could form a more stable 3 D crystalline structure and alleviate the decomposition caused by the humidity. It delivered a power conversion efficiency of 19.3 % upon preparation under a humid environment condition of 50 % relative humidity as well as improved humidity and thermal stability. Our work provides a facile strategy for improving perovskite performance and stability by introducing a new chemical additive for the future application of perovskite solar cells.

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Photochemical Transformation of Fullerenes

Cited by 39 publications

References 41 publications

Synergetic enhancement of organic solar cell thermal stability by wire bar coating and light processing

Synergetic enhancement of organic solar cell thermal stability by wire bar coating and light processing

Performance enhancement of fullerene-based solar cells by light processing

Fabrication of Efficient and Stable Perovskite Solar Cells in High‐Humidity Environment through Trace‐Doping of Large‐Sized Cations

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