Research Projects

The proposed research aims to advance high-efficiency, cost-effective, and environmentally friendly photovoltaic (PV) technologies by developing antimony sulfide (Sb₂S₃) based PV devices. Sb₂S₃ is a stable, non-toxic material with a high absorption coefficient greater than 10⁵ cm⁻¹, allowing a mere 500 nm thin film to absorb 98% of sunlight. This could lead to considerable material and cost savings. Additionally, Sb₂S₃ possesses a quasi-one-dimensional (Sb₄S₆)n ribbon structure, where the electron density is confined within these ribbons. This suggests that grain boundaries in (hk1) oriented Sb₂S₃ grains could be electronically benign. Despite its promise, existing Sb₂S₃-based PV devices struggle with power conversion efficiency (PCE), primarily due to interface recombination and bulk defects leading to low open-circuit voltage (Voc). This proposal aims to overcome these challenges through well-defined objectives. 1. Synthesis of (hk1) oriented Sb₂S₃ thin films: This objective aims to synthesize Sb₂S₃ thin films via a solution process, investigating the effects of various substrates and interfacial contact layers, along with other growth parameters to achieve (hk1)-oriented films. 2. Tuning of optoelectronic properties of Sb₂S₃: This objective aims to tailor the optoelectronic properties of Sb₂S₃ by doping/alloying with external elements. Emphasis will be placed on identifying deep-energy level defects, their nature, and their distribution. By controlling the composition and doping/alloying, we aim to minimize efficiency-limiting defects and enhance the VOC of Sb₂S₃ PV devices. 3. Development of cadmium-free contact layers: This objective focuses on preparing cadmium-free contact layers, such as Zn(O,S), (Zn,Ti)O, or (Zn,Sn)O, via chemical bath deposition, targeting conduction band offsets (CBO) between 0 - 0.3 eV. Achieving these CBO values is crucial for enhancing the PCE of PV devices. 4. PV device fabrication and investigation of elemental diffusion across the interfaces: This objective aims to fabricate PV devices by integrating optimized Sb₂S₃ absorber layer with engineered contact layers. Additionally, elemental diffusion across the interfaces will be studied using TEM and XPS to understand its impact on the PCE performance This proposal hypothesizes that tuning the optoelectronics properties of the Sb₂S₃ absorber layer, selecting suitable contact layers, and reducing interface recombination can significantly enhance the open-circuit voltage and, in turn, the efficiency of the Sb₂S₃ PV devices. The proposal aligns with India’s National Action Plan on Climate Change by addressing environmental challenges through the advancement of stable, cost-effective Sb₂S₃ PV technology. It also aims to nurture young scientists in the development and analysis of advanced photovoltaic devices.