Erroneous efficiency reports harm organic solar cell research

Zimmermann, Eugen; Ehrenreich, Philipp; Pfadler, Thomas; Dorman, James; Weickert, Jonas; Schmidt‐Mende, Lukas

doi:10.1038/nphoton.2014.210

Cited by 208 publications

(152 citation statements)

References 18 publications

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“…[25][26][27][28] This has prompted some critics to question the reported progress of the PSC fi eld, in comparison with other established photovoltaic (PV) technologies (e.g., Si). [ 29,30 ] In particular, the use of small-area devices has been criticized because the measurement errors tend to increase as the active cell area becomes smaller. Thus, the development of PSCs with active areas on the square-centimeter scale is recommended for the evaluation of a new PV technology.…”

Section: Doi: 101002/adma201502586mentioning

confidence: 99%

Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%

et al. 2015

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The preparation of uniform, high-crystallinity planar perovskite films with high-aspect-ratio grains over a square-inch area is demonstrated. The best power conversion efficiency (PCE) of 16.3% (stabilized output of ≈15.6%) is obtained for a planar perovskite solar cell (PSC) with 1.2 cm2 active area, and the PCE jumps to 18.3% (stabilized output of ≈17.5%) for a PSC with a 0.12 cm2 active area.

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Section: Doi: 101002/adma201502586mentioning

confidence: 99%

Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%

et al. 2015

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“…Importantly by using isopropanol-based ZnO solution to process the electron extraction layers we could combine alcoholic post-treatment required to reach high efficiency with PTB7-Th in air with solution-based deposition of the IL in one step rigorously simplify processing in ambient conditions. The demonstrated compatibility of polymer solar cells using solution-processed photoactive and interfacial layers with large active areas indicates that the introduction of a standard active area of 1 cm 2 for measuring efficiency of record solar cells, as commented recently, [47] is feasible. However electric standards for ITO or alternative transparent electrodes need to be developed so that performance of new photovoltaic materials or device structures can be compared at square centimeter-size.…”

Section: Discussionmentioning

confidence: 94%

Square‐Centimeter‐Sized High‐Efficiency Polymer Solar Cells: How the Processing Atmosphere and Film Quality Influence Performance at Large Scale

Dkhil

Pfannmöller

Bals

et al. 2016

Advanced Energy Materials

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International audienceOrganic solar cells based on two benzodithiophene-based polymers (PTB7 and PTB7-Th) processed at square centimeter-size under inert atmosphere and ambient air, respectively, are investigated. It is demonstrated that the performance of solar cells processed under inert atmosphere is not limited by the upscaling of photoactive layer and the interfacial layers. Thorough morphological and electrical characterizations of optimized layers and corresponding devices reveal that performance losses due to area enlargement are only caused by the sheet resistance of the transparent electrode reducing the effi ciency from 9.3% of 7.8% for PTB7-Th in the condition that both photoactive layer and the interfacial layers are of high layer quality. Air processing of photoactive layer and the interfacial layers into centimeter-sized solar cells lead to additional, but only slight, losses (< 10%) in all photovoltaic parameters, which can be addressed to changes in the electronic properties of both active layer and ZnO layers rather than changes in layer morphology. The demonstrated compatibility of polymer solar cells using solution-processed photoactive layer and interfacial layers with large area indicates that the introduction of a standard active area of 1 cm(2) for measuring effi ciency of organic record solar cells is feasible. However electric standards for indium tin oxides (ITO) or alternative transparent electrodes need to be developed so that performance of new photovoltaic materials can be compared at square centimeter-size

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“…The TC potential profiles had V c = 0, and therefore µ ch is calculated by replacing V ch with V D in Equations (3) and (4). The values of µ ch for all three structures are then compared to the mobility extracted by derivative-based methods:…”

Section: Parameter Extractionmentioning

confidence: 99%

“…[4] By contrast, widely discussed parameters (i.e., charge-carrier mobility and threshold voltage, V T ) for organic field-effect transistors (OFETs) are model parameters, meaning that the numbers are inherently dependent on the model used as well as the procedure followed to implement this model. [5,6] Therefore, the lack of consensus may lead to discrepancies in parameters extracted even from the same current-voltage curve.…”

mentioning

confidence: 99%

Potentiometric Parameterization of Dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene Field‐Effect Transistors with a Varying Degree of Nonidealities

Kim

Thomas

Kim

et al. 2018

Adv Elect Materials

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in a fully standardized manner with, for instance, no extra light, heat, or active areas involved. [4] By contrast, widely discussed parameters (i.e., charge-carrier mobility and threshold voltage, V T ) for organic field-effect transistors (OFETs) are model parameters, meaning that the numbers are inherently dependent on the model used as well as the procedure followed to implement this model. [5,6] Therefore, the lack of consensus may lead to discrepancies in parameters extracted even from the same current-voltage curve.In 2004, Horowitz et al. summarized and extended a series of their earlier works to clarify nonidealities, or disagreement with metal-oxide-semiconductor field-effect transistors (MOSFETs) in OFET devices. [7] As illustrated here, gate-voltage (V G ) dependence of mobility and existence of the contact resistances (R c ) are two common and theoretically justifiable sources of deviations from ideal MOSFET characteristics. Until recently, many experimental studies employed techniques such as the transmission-line method (TLM) or gated fourpoint probe measurements (gFPP), which can in principle directly probe these phenomena by separating the channel and contact properties. [8][9][10][11][12][13][14] In our view, the reported data bring strong evidence for the pronounced variability in relative strengths, and voltage-or structure dependence of the contact and channel effects, which makes different theoretical frameworks often necessary to understand different devices. Nonetheless, the MOSFET current-voltage model has been employed quite universally for simple parameter extraction. In 2016, Gundlach and co-workers used impedance spectroscopy to systematically address mobility overestimation in rubrene single-crystal transistors, [15] an issue that in fact originates from neglecting R c and/or noncontextually adopting simplified equations. In this context, it is timely to critically reassess basic assumptions of the device parameters, specific behavioral nonidealities, and associated calculation issues. Ideally, growing efforts into such a process will be transformed into carefully thought-out and broadly accepted practices for OFET research.In this article, we report on the use of scanning Kelvin probe microscopy (SKPM) and correlated analysis aimed at generalizable parameterization. SKPM is a powerful, surface-sensitive technique that can directly probe critical resistive pathways in OFETs to quantify material-and interface-related parameters. Furthermore, SKPM holds some advantages over the TLM or gFPP in that neither averaging Taking full account of the contact effects and including an explicit threshold voltage in calculation are shown to be critical to access the intrinsic carrier mobility, while simple derivative-based extraction may over-or underestimate it. Further analytical developments correlate individual physical parameters, leading to the discovery that pentafluorobenzenethiol self-assembled on gold predominantly affects the carrier mobility rather than the injection barrier.

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Erroneous efficiency reports harm organic solar cell research

Abstract: Mischaracterization of so lar cell power conversion efficiencies and widespread publication of inconsistent data in scientific journals th reate ns to undermine progress in orga nic and hybrid photovoltaics research.

Cited by 208 publications

References 18 publications

Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%

Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%

Square‐Centimeter‐Sized High‐Efficiency Polymer Solar Cells: How the Processing Atmosphere and Film Quality Influence Performance at Large Scale

Potentiometric Parameterization of Dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene Field‐Effect Transistors with a Varying Degree of Nonidealities

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Erroneous efficiency reports harm organic solar cell research

Abstract: Mischaracterization of so lar cell power conversion efficiencies and widespread publication of inconsistent data in scientific journals th reate ns to undermine progress in orga nic and hybrid photovoltaics research.

Cited by 208 publications

References 18 publications

Square‐Centimeter Solution‐Processed Planar CH3NH3PbI3 Perovskite Solar Cells with Efficiency Exceeding 15%

Square‐Centimeter Solution‐Processed Planar CH3NH3PbI3 Perovskite Solar Cells with Efficiency Exceeding 15%

Square‐Centimeter‐Sized High‐Efficiency Polymer Solar Cells: How the Processing Atmosphere and Film Quality Influence Performance at Large Scale

Potentiometric Parameterization of Dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene Field‐Effect Transistors with a Varying Degree of Nonidealities

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Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%

Square‐Centimeter Solution‐Processed Planar CH₃NH₃PbI₃ Perovskite Solar Cells with Efficiency Exceeding 15%