Periodic Reporting for period 1 - PEARL (FLEXIBLE PEROVSKITE SOLAR CELLS WITH CARBON ELECTRODES)
Berichtszeitraum: 2023-10-01 bis 2025-03-31
Within the past decade perovskite solar cells (PSCs) have been a subject of intense research. The perovskite photo-absorptive materials offer inherent advantages leading to high power conversion efficiency, long carrier diffusion length, high carrier mobility, low exciton binding energy, high absorption coefficient and band gap tunability. These features, combined with the low-cost potential of the perovskite photovoltaic (PV) technology and the increasing electricity production from photovoltaic panels, the perovskite solar technology is expected to invade the conventional solar market first in tandem with existing silicon modules and later in low-cost panels of pure perovskite .
The possibility to deposit the perovskite thin films via solution-based processing enables high-throughput, cost-effective production of flexible and light-weight PSCs. This will further expand the commercialization potential of PSCs into variety of applications such as mobile electronic devices, vehicle- and building integrated PVs (VIPV, BIPV), building applied PV (BAPV) and Internet of Things (IoT) market. Despite the high power conversion efficiency (PCE) of 27.0% recorded for (rigid) perovskites at cell level, and stability surpassing the IEC certification standards, a successful implementation of the technology requires large-scale manufacturing methods reducing the production costs without the loss in efficiency.
The mainstream PV market is currently dominated by Asian producers of rigid crystalline silicon and glass-based PV products. Although these modules reach state-of-the-art efficiencies, their application areas are limited to surfaces that can bear the weight of the installed system and to areas not requiring customization (solar farms, rooftops). For broader application of PV, it is essential to apply them also on surfaces with aesthetic demands. Thus, flexibility in shape and size is a unique selling point of PSCs. Additionally, replacement of vacuum deposited metal electrodes with alternative, printable electrode (carbon) significantly reduces the CO2 footprint and the cost of the flexible perovskite PV.
The communication of European Commission strongly emphasizes the importance of bringing PV production back to Europe. One of the few competing areas that Europe can win is building up the processing infrastructure for flexible thin film photovoltaics, since this type of market product is not yet well established in the Asian factories. In PEARL, the participation of perovskite PV supplier partner Saule Technologies and their pioneering incentives on flexible perovskite PV is an important attempt to bring the PV production back to Europe.
The recent development of flexible PSCs has led to a world record efficiency of 24.9% by Tsinghua University, Beijing, China (doi: 10.23919/IEN.2024.0001). The primary objectives of PEARL are to realise flexible PSCs processed with industrially viable, scalable and environmentally sustainable thin film technologies, efficiency of >25% at cell and 22.5% at module level, showing long term operational stability surpassing the IEC standards, lowered production costs below 0.3 €/Wp, minimal emissions <0.01 kg CO2eq/kWh and high circularity through recycling of valuable materials. To reach the objectives, PEARL is focusing on the development of planar, conventional n-i-p, and further n-i-c, device architectures utilising low-temperature carbon pastes.
The possibility to deposit the perovskite thin films via solution-based processing enables high-throughput, cost-effective production of flexible and light-weight PSCs. This will further expand the commercialization potential of PSCs into variety of applications such as mobile electronic devices, vehicle- and building integrated PVs (VIPV, BIPV), building applied PV (BAPV) and Internet of Things (IoT) market. Despite the high power conversion efficiency (PCE) of 27.0% recorded for (rigid) perovskites at cell level, and stability surpassing the IEC certification standards, a successful implementation of the technology requires large-scale manufacturing methods reducing the production costs without the loss in efficiency.
The mainstream PV market is currently dominated by Asian producers of rigid crystalline silicon and glass-based PV products. Although these modules reach state-of-the-art efficiencies, their application areas are limited to surfaces that can bear the weight of the installed system and to areas not requiring customization (solar farms, rooftops). For broader application of PV, it is essential to apply them also on surfaces with aesthetic demands. Thus, flexibility in shape and size is a unique selling point of PSCs. Additionally, replacement of vacuum deposited metal electrodes with alternative, printable electrode (carbon) significantly reduces the CO2 footprint and the cost of the flexible perovskite PV.
The communication of European Commission strongly emphasizes the importance of bringing PV production back to Europe. One of the few competing areas that Europe can win is building up the processing infrastructure for flexible thin film photovoltaics, since this type of market product is not yet well established in the Asian factories. In PEARL, the participation of perovskite PV supplier partner Saule Technologies and their pioneering incentives on flexible perovskite PV is an important attempt to bring the PV production back to Europe.
The recent development of flexible PSCs has led to a world record efficiency of 24.9% by Tsinghua University, Beijing, China (doi: 10.23919/IEN.2024.0001). The primary objectives of PEARL are to realise flexible PSCs processed with industrially viable, scalable and environmentally sustainable thin film technologies, efficiency of >25% at cell and 22.5% at module level, showing long term operational stability surpassing the IEC standards, lowered production costs below 0.3 €/Wp, minimal emissions <0.01 kg CO2eq/kWh and high circularity through recycling of valuable materials. To reach the objectives, PEARL is focusing on the development of planar, conventional n-i-p, and further n-i-c, device architectures utilising low-temperature carbon pastes.
By M18 of the PEARL project, extensive activities on material and device concept development have been made. The materials developed include functionalized substrates with transparent electrode and barrier layers, perovskite light absorbing materials, charge transporting and passivation materials, carbon inks, barrier adhesives and antireflective coating materials. Progress has been made in all fronts and the main achievements include 1) the specification of unified solar cell stacks for both metal and carbon top electrodes, 2) optimization of the functionalized substrate stack for improved processability, 3) modification of the materials and solar cell stack to achieve PCE above 21% on flexible substrate, 4) modification of the carbon inks for improved cell performance and 5) development of entirely new barrier adhesives and antireflective coatings. All the material and device developments have been optimized in a way that they are scalable and safe to fabricate. Additionally, an initial life-cycle analysis has been performed where the main factors causing impacts in the PV production phase have been identified.
During the first 18 months of PEARL, power conversion efficiency of 21.6% on flexible PSCs with metal top electrode has been reached. The improvement has mainly been reached by the interface passivation and optimization of the bulk perovskite quality. Further increase in the performance is expected when the interface passivation materials are optimized further and when the antireflective coatings and high conductive electrodes will be applied to the flexible stack.
For the cells with Carbon top electrode, the PEARL objective is to reach efficiency >20% by project M30. By M18, the PSC with Carbon top electrode has already doubled the efficiency from 5.2% to 10.03%. The key improvements made in the perovskite layer and in the cell architecture were:
• Modification of the solvent system in the perovskite ink.
• Optimization of the perovskite annealing conditions.
• Introduction of a new HTL layer.
Further improvement in the efficiency of Carbon cells is expected when the interface passivation strategies from the metal cells will be applied. Also, utilization of the antireflective coating will improve the efficiency of the Carbon cells.
Notably, the cells with metal top electrodes have been processed from DMF:DMSO solvent system under inert atmosphere with antisolvent quenching method whereas the Carbon cells have been processed under ambient conditions using only green solvents without any antisolvent. Also, while the metal cells utilize spin-coating as the deposition technology, the thin films in Carbon cells have been processed using scalable blade-coating and screen-printing methods (blade coating for ETL, perovskite and HTL, and screen-printing for Carbon).
For the PEARL stack, it has been identified that the encapsulation is the main cause for environmental impacts. The next largest impacts result from the transparent electrode, perovskite layer and carbon electrode, respectively. The high impacts result mainly from the vacuum-based processing of the functional layers in the encapsulation and transparent electrode.
For the cells with Carbon top electrode, the PEARL objective is to reach efficiency >20% by project M30. By M18, the PSC with Carbon top electrode has already doubled the efficiency from 5.2% to 10.03%. The key improvements made in the perovskite layer and in the cell architecture were:
• Modification of the solvent system in the perovskite ink.
• Optimization of the perovskite annealing conditions.
• Introduction of a new HTL layer.
Further improvement in the efficiency of Carbon cells is expected when the interface passivation strategies from the metal cells will be applied. Also, utilization of the antireflective coating will improve the efficiency of the Carbon cells.
Notably, the cells with metal top electrodes have been processed from DMF:DMSO solvent system under inert atmosphere with antisolvent quenching method whereas the Carbon cells have been processed under ambient conditions using only green solvents without any antisolvent. Also, while the metal cells utilize spin-coating as the deposition technology, the thin films in Carbon cells have been processed using scalable blade-coating and screen-printing methods (blade coating for ETL, perovskite and HTL, and screen-printing for Carbon).
For the PEARL stack, it has been identified that the encapsulation is the main cause for environmental impacts. The next largest impacts result from the transparent electrode, perovskite layer and carbon electrode, respectively. The high impacts result mainly from the vacuum-based processing of the functional layers in the encapsulation and transparent electrode.