mesoporous stack-titania (m-TiO 2 ), zirconia (ZrO 2 ), carbon (C)-is printable, C-PSCs are ideal for large scale production and, interestingly, some features that prevent degradation, i.e., lack of metal cathode [9] and organic HTM, [10] are also responsible for the simpler manufacturing process, paving the way for C-PSCs to move quickly from the lab to the market. This module architecture not only uses low-cost materials but can be produced by equipment that has a very low-capital cost thus reducing the barrier to commercialization of perovskite modules. Constraining the grain growth of the perovskite completely within the three mesoporous structures enables crystallization of the perovskite over large areas without the need for dynamic drying [11,12] to mimic the spin coating process. [13] There have been some reports demonstrating that C-PSC modules can be produced by screen printing, via registration of the overlapping layers, and can deliver between 10 and 11% power conversion efficiency (PCE) on 10 × 10 cm 2 substrates, with active areas ranging from 47.6 [7,14] to 70 cm 2 , [15] and, in particular, showing over 1 year stability under illumination, as reported by Grancini et al. [7] These results for C-PSC modules are even more remarkable, considering that modules with comparable active areas (>45 cm 2 ) and different device architecture, yielded respectively 12.6% PCE on 50.6 cm 2 (FTO/c-TiO 2 /graphene+m-TiO 2 / GO-Li/perovskite/spiro-OMeTAD/Au), [16] 8.7% PCE on 60 cm 2 (ITO/PEDOT:PSS/perovskite/PCBM/Au), [17] and 4.3% PCE on 100 cm 2 (FTO/c-TiO 2 /m-TiO 2 /perovskite/spiro-OMeTAD/ Au) [11] ; moreover, the record for PSC modules overall is Microquanta's 16% PCE [18,19] on just 16.29 cm 2 aperture area (active area + dead area for interconnections).Upscaling C-PSC manufacture from 10 × 10 cm 2 to larger substrate dimensions, e.g., A4 size as in our case, is far from trivial. Spraying the TiO 2 blocking layer (BL) at temperatures as high as 300 °C causes the large substrates to crack in the worst case or to bend, compromising the thickness homogeneity over the substrate of the printed layers, mostly and more crucially for the thinnest of the three, the sub-micrometric m-TiO 2 . Any change in the layers' thickness across the substrate can affect the performance of individual cells constituting the module Perovskite solar cells based on an all printable mesoporous stack, made of overlapping titania, zirconia, and carbon layers, represent a promising device architecture for both simple, low-cost manufacture, and outstanding stability. Here a breakthrough in the upscaling of this technology is reported: Screen printed modules on A4 sized conductive glass substrates, delivering power conversion efficiency (PCE) ranging from 3 to 5% at 1 sun on an unprecedented 198 cm 2 active area. An increase in the PCE, due to higher V OC and fill factor, is demonstrated by patterning the TiO 2 blocking layer. Furthermore, an unexpected increase of the performance is observed over time, while storing the modules in the dark,...

Near infrared sintering in less than 25 seconds for enhanced commercial viability of screen printed perovskite solar cells.

The fully printed, hole-transporter-free carbon perovskite solar cell structure incorporating a triple mesoscopic layer has emerged as a possible frontrunner for early industrialisation. It is an attractive structure because it can be fabricated by the simple sequential screen printing and sintering of titania, zirconia, and carbon. The device is finalised by manual dropping of a perovskite precursor solution onto the carbon which subsequently infiltrates. This stage in device fabrication is inhomogeneous, ineffective for large areas, and prone to human error. Here we introduce an automated deposition and infiltration system using a robotic dispenser and mesh which delivers the perovskite precursor uniformly to the carbon surface over a large area. It has been successfully used to prepare perovskite solar cells with over 9% efficiency. Cells, prepared by this robotic mesh deposition, showed comparable performance to reference cells, made by standard drop deposition, confirming this approach to be effective and reliable. X-ray diffraction and Raman spectroscopy were used to confirm the uniformity of the deposition over a large area. ARTICLE HISTORY

Indoor photovoltaics is one of the best sustainable and reliable energy source for low power consumption electronics such as the rapidly growing Internet of Things. Perovskite photovoltaic (PPV) cells with three benchmark device architectures – mesoporous PPV (mPPV) and inverted PPV (iPPV) with alternative hole transporting layers (HTLs), and carbon‐based PPV (cPPV) are studied under a simulated indoor environment. The mPPV cell using typical Spiro‐OMeTAD as the HTL shows the highest maximum power density (Pmax) of 19.9 μW cm−2 under 200 lux and 115.6 μW cm−2 under 1000 lux (without masking), which is among the best of the indoor PV. Interestingly, when PTAA is used as the HTL in the mPPV cell, the Pmax drops to almost zero under indoor light environment while its performance under one sun remains similar. On the other hand, when PEDOT:PSS is replaced by Poly‐TPD as HTL in the iPPV cell, the Pmax under indoor light improves significantly and is comparable to that of the best mPPV cell. This significant difference in indoor performance correlates well with their leakage current. The HTL‐free cPPV cell, prepared by fully up‐scalable techniques, shows a promising Pmax of 16.3 and 89.4 μW cm−2 under 200 and 1000 lux, respectively. A practical scale 5 × 5cm2 cPPV module is fabricated as a demonstration for real applications.

Enhancing fully printable mesoscopic perovskite solar cell performance using integrated metallic grids to improve carbon electrode conductivity, Current Applied Physics (2020), doi:

A range of slow dynamic processes occurring in perovskite solar cells have been linked to ionic migration, including J−V hysteresis and long photovoltage rise and decay times. This work demonstrates the remarkably slow response time of triple mesoporous carbon-based cells, containing the additive 5aminovaleric acid iodide (AVA). The photovoltage rise under illumination is 1−2 orders of magnitude longer than has previously been observed for planar and mesoporous TiO 2 based devices. Transient photovoltage measurements during this slow rise in voltage show a strong negative transient feature which demonstrates the presence of fast recombination. By analyzing the rate of V oc rise and the decay of this negative transient, we show a clear link between this recombination process and the limiting of the V oc . The reduction of recombination over time and the resultant rise in V oc are influenced by the movement of ions in the perovskite. From temperature-dependent measurements, an activation energy consistent with previous literature values for iodide ion migration is obtained, although the attempt frequency is found to be many orders of magnitude lower than that in pure MAPI perovskite devices. We attribute this to the presence of the AVA molecule inhibiting the movement of ions. The importance of the TiO 2 /ZrO 2 interface in leading to this slow behavior is revealed by studying devices with different architectures with and without the AVA additive. A significant increase in response time can only be recreated in a device with both of the mesoporous metal oxide layers and the AVA additive present in the perovskite.

The fully printable carbon triple-mesoscopic perovskite solar cell (C-PSC) has already demonstrated good efficiency and long-term stability, opening the possibility of lab-to-fab transition. Modules based on C-PSC architecture have been reported and, at present, are achieved through the accurate registration of each of the patterned layers using screen-printing. Modules based on this approach were reported with geometric fill factor (g-FF) as high as 70%. Another approach to create the interconnects, the so-called scribing method, was reported to achieve more than 90% g-FF for architectures based on evaporated metal contacts, i.e., without a carbon counter electrode. Here, for the first time, we adopt the scribing method to selectively remove materials within a C-PSC. This approach allowed a deep and selective scribe to open an aperture from the transparent electrode through all the layers, including the blocking layer, enabling a direct contact between the electrodes in the interconnects. In this work, a systematic study of the interconnection area between cells is discussed, showing the key role of the FTO/carbon contact. Furthermore, a module on 10 × 10 cm2 substrate with the optimised design showing efficiency over 10% is also demonstrated.

Perovskite solar cells have attracted a great deal of attention thanks to their high efficiency, ease of manufacturing, and potential low cost. However, the stability of these devices is considered their main drawback and needs to be addressed. Mesoporous carbon perovskite solar cells (m‐CPSC), consisting of three mesoporous layers (TiO2/ZrO2/C) infiltrated with CH3NH3PbI3 (MAPI) perovskite, have presented excellent lifetimes of more than 10 000 h when the additive NH2(CH2)4CO2HI (5‐ aminovaleric acid iodide; 5‐AVAI) is used to modify the perovskite structure. Yet, the role of 5‐AVAI in enhancing the stability has yet to be determined. Here, superoxide‐mediated degradation of MAPI m‐CPSC with and without the 5‐AVAI additive is studied using the fluorescence probe dihydroethidium for superoxide detection. In situ X‐ray diffractometry shows that aminovaleric acid methylammonium lead iodide (AVA‐MAPI) perovskite infiltrated in mesoporous layers presents higher stability in an ambient environment under illumination, evidenced by a slower decrease of the MAPI/PbI2 peak ratio. Superoxide yield measurements demonstrate that AVA‐MAPI generates more superoxide than regular MAPI when deposited on glass but generates significantly less when infiltrated in mesoporous layers. It is believed that superoxide formation in m‐CPSC is dependent on a combination of competitive factors including oxygen diffusion, sample morphology, grain size, and defect concentration.