Logotyp: till Uppsala universitets webbplats

The adoption of perovskite solar cells (PSCs) requires improved resistance to high temperatures and temperature variations. Hole-selective self-assembled monolayers (SAMs) have enabled progress in the performance of inverted PSCs, yet they may compromise temperature stability owing to desorption and weak interfacial contact. Here we developed a self-assembled bilayer by covalently interconnecting a phosphonic acid SAM with a triphenylamine upper layer. This polymerized network, formed through Friedel-Crafts alkylation, resisted thermal degradation up to 100°C for 200 h. Meanwhile, the face-on-oriented upper layer exhibited adhesive contact with perovskites, leading to a 1.7-fold improvement in adhesion energy compared with the SAM-perovskite interface. We reported power conversion efficiencies exceeding 26% for inverted PSCs. The champion devices demonstrated less than 4% and 3% efficiency loss after 2,000 h damp heat exposure (85°C and 85% relative humidity) and over 1,200 thermal cycles between -40°C and 85°C, respectively, meeting the temperature stability criteria outlined in the International Electrotechnical Commission 61215:2021 standards.

Perovskite solar cells (PSCs) hold significant promise as the next-generation materials in photovoltaic markets, owing to their ability to achieve impressive power conversion efficiencies, streamlined fabrication processes, cost-effective manufacturing, and numerous other advantages. The utilization of self-assembled monolayer (SAM) molecules has proven to be a significant success in enhancing device efficiency and extending device stability. This review highlights the dual use of SAM molecules in the realm of PSCs, which can not only serve as charge transport materials but also act as interfacial modulators. These research endeavors encompass a wide range of applications for various SAM molecules in both n-i-p and p-i-n structured PSCs, providing a deep insight into the underlying mechanisms. Furthermore, this review proposes current research challenges for future investigations into SAM materials. This timely and thorough review seeks to provide direction and inspiration for current research efforts dedicated to the ongoing incorporation of SAMs in the field of perovskite photovoltaics. Self-assembled monolayer (SAM) molecules are extensively employed in perovskite solar cells, serving both as charge transport materials and interfacial modulators. These molecules play a crucial role in adjusting surface energy levels, reducing interfacial trap defects, and enhancing perovskite crystallization quality, thereby leading to improved performance and stability of perovskite solar cells. image

Chemical environment and precursor-coordinating molecular interactions within a perovskite precursor solution can lead to important implications in structural defects and crystallization kinetics of a perovskite film. Thus, the opto-electronic quality of such films can be boosted by carefully fine-tuning the coordination chemistry of perovskite precursors via controllable introduction of additives, capable of forming intermediate complexes. In this work, we employed a new type of ligand, namely 1-phenylguanidine (PGua), which coordinates strongly with the PbI₂ complexes in the perovskite precursor, forming new intermediate species. These strong interactions effectively retard the perovskite crystallization process and form homogeneous films with enlarged grain sizes and reduced density of defects. In combination with an interfacial treatment, the resulted champion devices exhibit a 24.6% efficiency with outstanding operational stability. Unprecedently, PGua can be applied in various PSCs with different perovskite compositions and even in both configurations: n-i-p and p-i-n, highlighting the universality of this ligand.

Indoor photovoltaics (IPV) using dye-sensitized solar cells (DSCs) is one among the most promising ambient energy harvesting technologies used to realize self-powered Internet of Things (IoT), consumer electronics and portable devices. The emergence of new generation Cu(II/I) redox electrolytes used with co-sensitized organic dyes enables DSCs to realize higher open circuit photovoltages (V_oc) and power conversion efficiencies (PCE) under indoor/ambient illumination. Even though Cu(II/I) electrolytes are promising candidates, the recombination of electrons from the conduction band and sub-bandgap states to the oxidized Cu(II) species and slower regeneration of Cu(II) at the counter electrode limit their performance. Taking inspiration from the asymmetric redox behaviour exhibited by the conventional iodide/triiodide electrolyte, which is efficient in inhibiting the undesirable recombination process, we introduced an alternative strategy of modifying the coordination environment of Cu(II) metal center using the 2,9-dimethyl-1,10-phenanthroline (dmp) ligand. The resulting dual species [Cu(II)(dmp)₂Cl]⁺/[Cu(I)(dmp)₂]⁺ electrolyte exhibited an improved lifetime both under full sun and indoor illumination and better regeneration at the counter electrode. Employing this asymmetric dual species Cu(II)/Cu(I) electrolyte with the co-sensitized D35:XY1 dyes, we realized a record PCE of 35.6% under 1000 lux warm white CFL illumination.

Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight^1,2. Following a decade of advancement, Cu₂O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials^3,4,5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance⁶. Here we demonstrate performance of Cu₂O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu₂O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu₂O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu₂O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm⁻² current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.

The Editors-in-Chief for Journal of Materials Chemistry A, B and C look back at the 10th anniversary year and the celebratory activities that took place.

The Editors-in-Chief for Journal of Materials Chemistry A, B and C look back at the 10th anniversary year and the celebratory activities that took place.

The Editors-in-Chief for Journal of Materials Chemistry A, B and C look back at the 10th anniversary year and the celebratory activities that took place.

The stabilization of grain boundaries and surfaces of the perovskite layer is critical to extend the durability of perovskite solar cells. Here we introduced a sulfonium-based molecule, dimethylphenethylsulfonium iodide (DMPESI), for the post-deposition treatment of formamidinium lead iodide perovskite films. The treated films show improved stability upon light soaking and remains in the black α phase after two years ageing under ambient condition without encapsulation. The DMPESI-treated perovskite solar cells show less than 1% performance loss after more than 4,500 h at maximum power point tracking, yielding a theoretical T80 of over nine years under continuous 1-sun illumination. The solar cells also display less than 5% power conversion efficiency drops under various ageing conditions, including 100 thermal cycles between 25 °C and 85 °C and an 1,050-h damp heat test.