Sodium Alginate as a Natural Substrate for Efficient and Sustainable Organic Solar Cells

Abstract

Organic electronics, in particular organic photovoltaics, have gained widespread attention due to their unique properties such as lightness, flexibility, and low cost. Thanks to some recent breakthroughs in organic solar cells (OSCs) that exhibit power conversion efficiencies (PCEs) approaching 20%, this technology is slowly making its way into the market as a complementary solution to conventional photovoltaic devices. OSCs are well suited for high-end smart applications, ranging from building integration and Internet of Things to consumer electronics. However, up to now, little attention has been devoted to the environmental impact and sustainability of components and processes. It is thus necessary to develop a new generation of eco-designed devices without losing the level of performance. In this work, we report the fabrication of efficient and stable solution-processed OSCs built on a free-standing sodium alginate (SA) substrate. SA is a natural biodegradable polymer derived from brown algae. It is low-cost, nontoxic, abundant, water-processable, and easy to manipulate for the realization of homogeneous and transparent foils. SA-based OSCs exhibit PCEs from 1.8 to 7.2% and can be disassembled through a safe and sustainable biocatalyzed process, allowing selective and almost entire recovery of precious metals, such as Au and Ag, as well as the separation of all of the main components. This allows us to minimize the production of e-waste, in accordance with the requirements of sustainability and the circular economy.

Recycled or Bio-Based Solvents for the Synthesis of ZnO Nanoparticles: Characterization and Validation in Organic Solar Cells

“…Figure 6 shows the corresponding current density-voltage (J-V) curves. The photovoltaic performance of the resulting PTB7:PC 71 BM-based solar cells, consistent with analogous systems reported in the literature [16,22,23], are comparable, giving PCE values between 6.5 and 6.9%. This confirms the general quality and suitability of all the NP inks/films for photovoltaic applications, regardless of the adopted reaction solvent.…”

“…In view of a possible use of these inks on flexible and/or bio-based substrates [ 16 ], we investigated the effect of lower thermal treatments of the ZnO NP layers on the resulting device performance. To this end, instead of a thermal annealing at 120 °C for 10 min, used for the devices reported in Table 2 and Figure 6 , we treated the ZnO films at 85 °C for 20 min.…”

“…The device architecture comprised glass/ITO/ZnO/active blend/MoOx/Ag. In agreement with reference [16], patterned ITO-coated glasses (Rs~10 Ω/square) were cleaned in sequential sonicating baths (for 15 min) in deionized water, acetone, and isopropanol. After the final sonication step, substrates were dried with a stream of Ar gas and then placed in an oxygen plasma chamber for 5 min.…”

“…Recently, there has been a growing interest for the preparation of green-synthesized ZnO NPs for a variety of applications [ 10 , 11 , 12 ], even including photovoltaic devices [ 13 , 14 , 15 ]. Therefore, the possibility to develop alternative and less impacting methods/strategies to prepare ZnO NPs with controlled properties and improved performance is of relevant importance for the design of the next generation of more sustainable and efficient materials/components and devices [ 16 , 17 , 18 , 19 ].…”

Industrial waste against pollution: mill scale-based magnetic hydrogels for rapid abatement of Cr(vi)

“…Furthermore, all the expenses normally sustained for the disposal of this industrial waste can be avoided. From the economic point of view, the proposed adsorbent is characterized by a low impact: alginate is relatively cheap 68 and, eventually, it can be extracted in the laboratory from brown algae seaweeds; similar considerations can be done for ascorbic acid, which can be extracted from various vegetables scraps. Activated carbon is the most expensive component, but after encapsulation inside the bubble structure a smaller amount (in comparison to free powder) is enough to obtain complete Cr( vi ) removal, limiting the increase of adsorbent cost.…”