ORCID Profile
0000-0003-4409-8751
Current Organisation
Princeton University
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Publisher: American Chemical Society (ACS)
Date: 29-10-2013
DOI: 10.1021/CM4022563
Publisher: Wiley
Date: 09-12-2022
Abstract: Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in erse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open‐circuit voltage, short‐circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application, and are put into perspective using, e.g., the detailed balance efficiency limit. The 3rd installment of the “Emerging PV reports” extends the scope toward triple junction solar cells.
Publisher: Wiley
Date: 17-06-2013
Publisher: AIP Publishing
Date: 21-05-2018
DOI: 10.1063/1.5030885
Abstract: While it has recently been recognized that organic donor-acceptor charge transfer (CT) state energies can vary substantially under different interfacial morphologies, this behavior is under-appreciated in the context of organic singlet fission solar cells where a specific alignment between the triplet state of the fission material and the CT state of the donor-acceptor interface is necessary to the function of the device. In this work, we demonstrate that the CT state energy of a prototypical pentacene-C60 singlet fission system is around 1 eV in most systems, but can vary over 300 meV depending on the composition and morphology of the interface. Moreover, we show that the inclusion of a poly(3-hexylthiophene-2,5-diyl) underlayer, which commonly serves as a triplet blocker and hole collector in pentacene/C60 solar cells, helps promote active layer morphologies with stabilized, low energy CT states. These trends in the interfacial energetics are correlated with structural characterization of the films by atomic force microscopy and x-ray diffraction.
Publisher: Springer Science and Business Media LLC
Date: 22-11-2019
Publisher: Wiley
Date: 04-12-2020
Publisher: American Chemical Society (ACS)
Date: 30-12-2020
Publisher: Elsevier BV
Date: 12-2022
Publisher: Wiley
Date: 11-11-2021
Abstract: Following the 1st release of the “Emerging photovoltaic (PV) reports” , the best achievements in the performance of emerging photovoltaic devices in erse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2020. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open‐circuit voltage, short‐circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application and are put into perspective using, e.g., the detailed balance efficiency limit. The 2nd instalment of the “Emerging PV reports” extends the scope toward tandem solar cells and presents the current state‐of‐the‐art in tandem solar cell performance for various material combinations.
Publisher: American Chemical Society (ACS)
Date: 10-01-2020
DOI: 10.1021/JACS.9B12526
Abstract: Organic photovoltaic (OPV) efficiencies continue to rise, raising their prospects for solar energy conversion. However, researchers have long considered how to suppress the loss of free carriers by recombination-poor diffusion and significant Coulombic attraction can cause electrons and holes to encounter each other at interfaces close to where they were photogenerated. Using femtosecond transient spectroscopies, we report the nanosecond grow-in of a large transient Stark effect, caused by nanoscale electric fields of ∼487 kV/cm between photogenerated free carriers in the device active layer. We find that particular morphologies of the active layer lead to an energetic cascade for charge carriers, suppressing pathways to recombination, which is ∼2000 times less than predicted by Langevin theory. This in turn leads to the buildup of electric charge in donor and acceptor domains-away from the interface-resistant to bimolecular recombination. Interestingly, this signal is only experimentally obvious in thick films due to the different scaling of electroabsorption and photoinduced absorption signals in transient absorption spectroscopy. Rather than inhibiting device performance, we show that devices up to 600 nm thick maintain efficiencies of >8% because domains can afford much higher carrier densities. These observations suggest that with particular nanoscale morphologies the bulk heterojunction can go beyond its established role in charge photogeneration and can act as a capacitor, where adjacent free charges are held away from the interface and can be protected from bimolecular recombination.
Publisher: IOP Publishing
Date: 16-11-2017
Publisher: American Chemical Society (ACS)
Date: 29-01-2013
DOI: 10.1021/CM301910T
Publisher: American Chemical Society (ACS)
Date: 18-06-2019
No related grants have been discovered for Barry Rand.