Markus Kohlstädt | Fraunhofer ISE: How do we diagnose and eliminate contact resistance in laminated carbon back electrodes?
00:11:30 - 00:13:50
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How do we diagnose and eliminate contact resistance in laminated carbon back electrodes?
While printing carbon back electrodes on perovskite cells eliminates scarce noble metals, laminated carbon interfaces suffer from high series and contact resistances. Cross-sectional scanning electron microscopy (SEM) reveals that laminated carbon films are highly porous and prone to forming microscopic voids at the interface with the underlying charge transport or transparent conducting oxide (TCO) layer. These voids restrict the effective interfacial contact area, severely bottlenecking current extraction and limiting overall power conversion efficiency.
To characterize these current bottlenecks, researchers utilize Dark Lock-In Thermography (DLIT) paired with physical simulations to visualize localized current pathing and resistive heating. In high-resistance states, DLIT captures severe localized Joule heating confined strictly to the margins where the carbon electrode and ITO overlap. By optimizing the lamination temperature and applying a post-lamination solvent treatment, the carbon film consolidates, closing interfacial voids and establishing a uniform current density distribution across the active area.
Mitigating these interfacial contact resistances unlocked a massive performance boost, allowing carbon-electrode-based devices to achieve over 20% power conversion efficiency. This proves that with precise interfacial engineering and advanced electro-thermal diagnostics, low-cost, solvent-free laminated carbon can rival gold and silver back electrodes in performance while vastly improving device stability.
In this short video, you can learn:
* How microscopic voids and high porosity at the laminated carbon-TCO interface drive up contact resistance.
* How to use Dark Lock-In Thermography (DLIT) to visualize current distribution and localize resistive heating in solar cell electrodes.
* The post-lamination solvent treatment process used to compact carbon layers and establish homogeneous current pathways.
📋 **Clip Abstract** This clip investigates the physical origin of high contact and series resistance in laminated carbon back electrodes for perovskite solar cells. By pairing SEM imaging with Dark Lock-In Thermography, the presenter demonstrates how a post-lamination solvent treatment eliminates interfacial voids to achieve over 20% cell efficiency.
#DarkLockInThermography, #LaminatedCarbonElectrodes, #PostLaminationSolventTreatment, #InterfacialEngineering, #PerovskiteSolarCells, #PrintedElectronics
This is a highlight of the presentation:
Sustainable Fabrication of Perovskite Modules: Strategies for scalable devices with low material criticality
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00:01:48 - 00:03:22
Is the global mining industry ready to support a terawatt-scale perovskite solar transition?
Is the global mining industry ready to support a terawatt-scale perovskite solar transition?
Scaling perovskite photovoltaics to a terawatt peak capacity demands a critical re-evaluation of material supply chains. While laboratory-scale devices boast high efficiencies using noble metals like gold and silver, these materials present severe scalability bottlenecks due to extreme cost and finite mineral production. Furthermore, even seemingly abundant dopants like cesium present unanticipated supply vulnerabilities, not because of geological scarcity, but due to low current global mining throughput.
Beyond resource constraints, metal-based back electrodes introduce detrimental degradation pathways that limit long-term module stability. Under operational conditions, gold atoms migrate aggressively through the functional layer stack, causing severe performance drops over time. Similarly, silver-based counter electrodes react with migrating halide species to form silver iodide, causing rapid device failure.
To secure a commercial future for perovskite PV, research must pivot toward low-environmental-impact architectures that bypass these critical elements. Transitioning to earth-abundant materials, printed carbon back electrodes, and indium-free transparent conductive oxides (TCOs) is no longer just a research interest, but a strict commercial necessity for high-volume manufacturing.
In this short video, you can learn:
* Why current cesium mining rates pose a surprise supply chain threat for terawatt-scale perovskite deployment.
* How gold migration and silver iodide formation degrade metal-based back electrodes over operational lifetimes.
* The material strategy rules required to design robust, earth-abundant charge transport layers and contact electrodes.
📋 **Clip Abstract** This clip analyzes the material criticality and degradation mechanisms associated with scaling perovskite solar cells to terawatt peak capacities. It highlights why precious metals and cesium must be designed out of modern cell architectures to ensure both resource viability and long-term device stability.
#PerovskitePhotovoltaics, #PrintedCarbonElectrodes, #IndiumFreeTCOs, #CesiumSupplyChain, #PrintedElectronics, #TerawattScalePV
00:03:58 - 00:05:56
Can bio-based green solvents eliminate toxic anti-solvent quenching in perovskite manufacturing?
Can bio-based green solvents eliminate toxic anti-solvent quenching in perovskite manufacturing?
Transitioning perovskite processing from hazardous solvents like DMF and DMSO to green alternatives is critical for industrial manufacturing. This work evaluates gamma-valerolactone (GVL), a bio-based, non-toxic solvent derived from biomass, for depositing formamidinium lead triiodide (FAPbI3) films. However, GVL presents unique solubility limits, and attempting to increase precursor concentration via heating triggers an unexpected inverse crystallization behavior, precipitating both alpha and delta perovskite phases directly from the solution.
Despite this thermodynamic challenge, GVL-based processing offers a massive operational advantage over traditional solvent systems. While conventional DMF/DMSO formulations require precise anti-solvent quenching steps during spin-coating to lock in the precursor state, GVL-processed films can be deposited without any anti-solvent treatment. A mild subsequent annealing step is sufficient to selectively and exclusively crystallize the highly sought-after, photoactive alpha-phase FAPbI3.
Morphological analyses demonstrate that optimized GVL-processed thin films achieve dense, highly uniform grain structures equivalent to those processed from toxic benchmarks. This processing route yielded stable solar cells exceeding 21% power conversion efficiency, proving that green solvent formulations can match the performance of hazardous chemicals while dramatically simplifying the manufacturing pipeline.
In this short video, you can learn:
* How gamma-valerolactone behaves as a green, bio-based solvent alternative for FAPbI3 perovskite deposition.
* The mechanics of inverse crystallization in GVL and why heating the precursor solution limits solute concentration.
* How to eliminate toxic anti-solvent quenching steps while still achieving exclusive, highly crystalline alpha-phase FAPbI3.
📋 **Clip Abstract** This clip details the successful fabrication of highly efficient FAPbI3 perovskite solar cells using gamma-valerolactone, a non-toxic bio-based green solvent. The researchers demonstrate that this formulation bypasses the need for complex anti-solvent quenching steps, yielding high-quality, photoactive alpha-phase thin films via direct thermal crystallization.
#GammaValerolactone, #FAPbI3, #AntiSolventFree, #InverseCrystallization, #PerovskitePhotovoltaics, #GreenSolventProcessing