Ranbir Singh

Solution processability and temperature-induced fast crystallization lead to various defects at the surface of perovskite films, which act as the epicenters of non-radiative recombination loss. Therefore, eliminating these surface defects through effective passivation is of utmost importance. Herein, we introduce two small-molecular donor–acceptor–donor (D–A–D) interface passivators, namely, 4,4′-(dipyrido[3,2-a:2′,3′-c]phenazine-10,13-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (PNQP) and 4,4′-(dipyrido[3,2-a:2′,3′-c]phenazine-11,12-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (PNQO), by varying the substitution position of the donor triphenylamine motifs. By simply relocating the donor arms in PNQO, the π-conjugated heterocyclic core is pushed outward, establishing direct contact with the perovskite surface and significantly strengthening the perovskite/HTM interfacial interaction while reducing interfacial defect recombination. For PNQO, the enhanced dipole moment leads to a better charge-separated state and improved hole mobility, facilitating the healing of surface defects by chelating with uncoordinated Pb²⁺ through a Lewis acid–base interaction. The modulation of regioisomeric configurations to enhance passivation efficacy has been systematically investigated through a combination of comprehensive theoretical and experimental approaches. Remarkably, the PNQO-treated PSCs delivered a champion power conversion efficiency (PCE) of 31.50% under an indoor 1000 lx white LED, which is higher than that of the control device without passivation layer treatment (25.32%). In addition, the PNQO-treated PSCs exhibited an improved PCE of 18.74% under AM 1.5G illumination, which is higher than that of the control device (16.64%). After 1560 hours of storage under ambient conditions, the unencapsulated device retained 91% of its initial PCE, outperforming the control device, which could achieve only 41%. This study establishes a design strategy for a small molecular passivation layer to enhance the efficiency and stability of PSCs in the future.

Tin oxide (SnO ₂ ) has been widely used as an electron transport layer (ETL) in perovskite solar cells (PSCs) due to the excellent charge transport properties. In this work, we present a comprehensive computational and experimental investigation of a low‐temperature strategy for developing Mg‐doped SnO ₂ (Mg‐SnO ₂ ) as an ETL to enhance the performance of indoor perovskite solar cells (i‐PSCs). Experimental results demonstrate that Mg incorporation enhances optical transparency, increases the bandgap, and improves charge transport by reducing charge recombination at the ETL/perovskite interface. These enhancements lead to superior PCEs, achieving 35.54% under indoor LED illumination and 20.28% under standard one sun conditions, significantly outperforming undoped SnO ₂ ‐based devices. Complementary density functional theory (DFT) simulations support the experimental findings, revealing that Mg doping decreases deep trap states, and contribute to improved ETL conductivity. The strong correlation between theoretical predictions and experimental outcomes underscores the effectiveness of Mg‐SnO ₂ as a high‐performance and stable ETL for indoor photovoltaic applications. This study establishes a practical pathway for developing optimized Mg‐doped electron transport layer for efficient indoor light harvesting.

Perovskite solar cells offer a transformative path for renewable solar energy, yet their sustainability relies upon addressing lead toxicity through recycling and reusing to convert this emerging technology into a circular economy model.

Design and fabrication of a stable PVA/NaNO ₃ gel-soaked sponge for high-performance TENGs, delivering an output voltage of 61 V and a current of 1.6 µA, enabling real-time sensors for wearable electronics.

The development of artificial electronic skin (e‐skin) that replicates the tactile sensing capabilities of human skin offers transformative potential for intelligent robotics and next‐generation wearable technologies. However, achieving compact, energy‐efficient integration of multiple sensing modalities within a single platform remains a significant challenge. Here, we present a bio‐inspired microchanneled e‐skin, functioning as a microchanneled triboelectric nanogenerator (MC‐TENG), that enables self‐powered, multimodal sensing in a unified framework. The device incorporates a conducting gel synthesized by dispersing graphene nanoplatelets (GNPs) into a polyvinyl alcohol/sodium nitrate matrix (PVA/NaNO ₃ /GNPs), resulting in enhanced mechanical robustness with tensile and compressive strengths of 0.41 and 2.8 MPa, respectively. The MC‐TENG generates an output current of approximately 5.6 µA, with voltage and power outputs reaching 39.9 V and 0.44 mW, sufficient for operating low‐power electronics and detecting human motion. Fabricated e‐skin demonstrates excellent pressure, temperature, and stiffness sensitivity of ~1.81 V/kPa, ~42.7 mV/K, and ~7.43 × 10 ⁻⁶ V/Nm ⁻¹ , respectively. Further, integration with a robotic arm enables functionalities such as object recognition, texture identification, and thermal sensing. This scalable, low‐cost, and self‐sustaining e‐skin platform represents a promising route toward more perceptive and interactive robotic systems, as well as advanced human‐machine interfaces.

Triboelectric nanogenerators (TENG) is a promising and sustainable solution for converting mechanical energy into electrical energy, as well as utilize for energy harvesting and sensing applications. However, TENG devices inherently suffers from limited electrical conductivity, which limits output current from dielectric triboelectric layers despite their high voltage generation. To address these challenges, this work presents the development of high-performance polyvinyl alcohol/silver nitrate (PVA/AgNO₃) conducting gels, engineered to be flexible, stretchable, and employed as an electropositive intermediate dielectric layer embedded within the TENG architecture to facilitate efficient charge generation and transfer. Synthesized PVA/AgNO₃ conducting gel exhibits improved electrical conductivity, tensile strength, and compressive strength of 32.8 S/m, 0.5 MPa, and 0.6 MPa, respectively. Further, conducting gel was employed to fabricate a triboelectric nanogenerator (CG-TENG), delivering an output voltage of 27.6 V and a current density response up to 0.4 μA/cm², which is a threefold increment compared to reference conducting gel free-TENG. The CG-TENG efficiently produces a maximum power density of 0.16 mW/cm² across a 1 kΩ load resistor. Additionally, a 2 × 2 self-powered pressure sensor array prototype was fabricated using CG-TENG to demonstrate spatially resolved pressure sensing, where each pixel generated distinct electrical signals under mechanical stimulation. The prototypes successfully demonstrate emergency alert messages on OLED, wirelessly visualize pressure sensing and distribution on the graphical user interface (GUI).

Indoor bifacial photovoltaics (i‐BPVs) have drawn a lot of interest as a possible option for efficiently absorbing light from artificial indoor light sources. Comparing other emerging PV technologies, perovskite‐based i‐BPVs (i‐BPPVs) have shown superior device performance under artificial light sources with affordable fabrication cost. Nonetheless, designing i‐BPPVs to efficiently harvest energy from indoor light sources remains both challenging and attractive research field. This study mainly focuses on the simulation of i‐BPPVs, aiming to optimize their performance under various ideal and non‐ideal conditions using SCAPS‐1D. The effects of various parameters such as series and shunt resistance, perovskite layer thickness, interfacial defects, irradiance power, and temperature are investigated under indoor light environments. Designed bifacial architecture Glass/ITO/SnO ₂ /MAFAPbI ₃ /Spiro‐OMeTAD/ITO have shown power conversion efficiencies (PCE) of 33.74% and 23.45%, when exposed from top‐ and bottom‐sides, respectively, employing nearly realistic operating conditions. The outcomes of this simulation study provide crucial insights into the design and development of next‐generation i‐BPPVs, opening the door to more efficient and sustainable indoor energy harvesting options.