Francesca Brunetti

Perovskite solar cells (PSCs) offer exceptional tunability of optoelectronic properties, enabling wide-band-gap absorbers that are highly attractive for semitransparent devices in building-integrated photovoltaics (BIPV). However, challenges associated with stability, scalability, and materials’ cost continue to limit their practical deployment, highlighting the pivotal role of hole transport materials (HTMs) in achieving high efficiency and durable device operation. Herein, we report the rational design and synthesis of three novel small-molecule HTMs based on phenothiazine–triarylamine cores, prepared via concise synthetic routes with moderate-to-high yields. The electron-rich, nonplanar phenothiazine scaffold enables suppressed aggregation and favorable energy-level alignment, rendering these materials particularly suitable for wide-band-gap and semitransparent PSCs. When implemented in FAPbBr₃-based semitransparent devices, two candidates (SM1 and SM2) achieve power conversion efficiencies comparable to those of the state-of-the-art poly(triarylamine) (PTAA) (PCE = 6.26% and 6.09% for SM1 and SM2, respectively, vs 6.39% for PTAA). Notably, their enhanced optical transparency leads to comparable light-utilization efficiency (LUE) (4.05 and 3.99 for SM1 and SM2, respectively, vs 4.07 for PTAA), with outstanding and superior bifaciality factors (84% and 82% for SM1 and SM2, respectively, vs 81% for PTAA), providing a distinct advantage beyond conventional opaque-PV efficiency metrics. These findings position phenothiazine-based HTMs as promising, cost-effective alternatives to PTAA for scalable semitransparent perovskite solar cells.

Material synthesis and supercapacitor device fabrication based on a TiO ₂ @DND composite over carbon interdigitated electrodes and the scheme of the subsequent charge storage mechanism.

A fully printed energy storage device on consumer paper was developed, combining low-cost fabrication, mechanical flexibility, eco-friendly materials, and reliable performance for disposable and wearable electronics applications.

Flexible perovskite solar cells hold promise of being an enabling technology for space missions: by reducing the encumbrance and weight of the payload's power system, launch costs can be minimized. The increased interest, however, must be accompanied by thorough testing under a broad range of space‐related sources of degradation and investigation of their effects on the layer stack. In this work, the resilience against atmospheric neutron radiation (9 particles/cm² irradiation, 380 times higher than the yearly fast neutron fluence in low Earth orbit, the devices show good stability, with efficiency losses below 20%. Further investigation by light intensity‐dependent JV scans, hyperspectral photoluminescence microscopy, X‐ray diffraction, X‐ray reflectivity, and atomic force microscopy reveals that the neutron radiation mainly affects the perovskite/hole transport layer interface, to a different extent depending on the material. This work confirms that accelerated stress testing is an important tool to determine the feasibility of this technology for space applications and provides insights on the damages caused by atmospheric neutrons which will help inform future decisions for the fabrication of space‐resilient flexible perovskite solar cells.

Integrating dye-sensitized solar cells with polyviologen-based supercapacitors enables efficient ambient light harvesting and storage, achieving 30% power conversion efficiency under indoor lighting conditions to power edge computing IoT networks.

Interfaces pose significant challenges to the performance and stability of perovskite solar cells (PSCs), as defects and weak interactions at these boundaries can lead to energy losses and degradation. To address these issues, it is crucial to functionalize hole transport materials (HTMs) to effectively manage interfacial defects and enhance charge transfer. This study introduces a carbazole‐based hole transport layer (TC‐ICA) that leverages halogen bonding (XB) for enhanced interface passivation with the perovskite layer and carboxylic group anchoring to the indium‐doped tin oxide (ITO). By combining these functionalities, the TC‐ICA material leads to exceptional device stability (99% shelf stability over 320 days of air storage and a T₈₀‐lifetime exceeding 1000 h under light soaking) and enhanced efficiency (15.4%), outperforming single‐function materials like TC‐CA (14.7%) and TC‐I (10.7%). This dual‐function strategy marks a significant advancement in the quest for high‐performance and long‐term stable PSCs.

Flexible perovskite solar cells (F-PSCs) are highly promising for harvesting solar energy in various environments, both indoors and outdoors. Nonetheless, one of the main hurdles to the widespread commercial use of F-PSCs is the thermal evaporation of the metal top electrode, a time-consuming process that substantially increases the cost related to both raw materials and fabrication equipment. Consequently, developing effective alternatives is essential for harnessing the full potential of this technology. One promising approach is to replace the top metal electrode with carbon-based materials, which can effectively serve as both the hole transport layer (HTL) and back electrode. These materials are low cost and compatible with inexpensive, simple, and scalable deposition techniques, such as blade coating. However, HTL-free carbon-based PSCs (C-PSCs) currently suffer from power conversion efficiency (PCE) lower than their metal counterparts, due to inefficient charge transfer and collection, associated with an ineffective perovskite (PVK) and carbon electrode interface. By utilizing a suitable HTL between the PVK and the carbon electrode, the charge extraction can be effectively improved and the interfacial recombination reduced. Throughout this work, a screening of suitable hole transport materials (HTMs) was carried out to select the most promising candidate to improve the performance of C-PSCs on flexible substrates. Copper(I) thiocyanate (CuSCN) was employed as the HTL with a wide band gap (3.5–3.8 eV). At the optimized concentration of 10 mg ml⁻¹, a PCE of 9.4% was achieved on 1 cm² flexible devices. The results obtained were compared with the performance of F-PSCs with gold top electrodes using organic PTAA as the HTL as state-of-the-art reference. The optimization of the HTL allowed for the demonstration of a significant improvement in the performance of the device, which could pave the way for the large-scale commercialization of PSCs with low environmental impact and promising cost-effectiveness.