Research Projects

Rationale of the Research- Perovskite solar cells (PSCs) represent a rapidly advancing photovoltaic technology due to their high efficiency and cost-effective fabrication. However, issues related to interface instability, defect-mediated charge recombination, and sensitivity to moisture continue to hinder their long-term reliability. These problems primarily originate at the buried interfaces between the perovskite absorber and charge transport layers, which are structurally and electronically disordered. Traditional approaches using small molecules or polymers for interfacial passivation often lack precision, structural definition, and stability. Therefore, a rationally designed interface-modifying material with defined geometry, multifunctionality, and robust binding characteristics is essential to overcome these challenges. Scientific Objectives- This project aims to synthesize and explore a novel ligand, 2,6-Bis(1-hexylbenzimidazol-2-yl)-4-phosphonopyridine (BBIP-Hex-Phos), and its metal coordination complexes with Zn(II), Cu(I/II), Fe(II/III), and Co(II/III). These complexes are designed to serve as multifunctional interlayers between the perovskite and transport layers to improve interface quality, passivate trap sites, and resist environmental degradation. The specific objectives include: 1. Synthesizing BBIP-Hex-Phos–metal complexes through a controlled and reproducible process. 2. Performing comprehensive structural and electronic characterization. 3. Applying these complexes at PSC interfaces using optimized deposition techniques. 4. Evaluating device performance and stability enhancements resulting from interfacial modification. Hypothesis to be Tested- It is proposed that BBIP-Hex-Phos–metal complexes, due to their coordinated tridentate core, phosphonic anchoring group, and hydrophobic alkyl chains, will reduce surface recombination, align interfacial energy levels, and suppress moisture-induced degradation when used as interlayers in PSCs. Main Experiments to be Carried Out- 1. Ligand–metal complexes will be synthesized and characterized using NMR, FTIR, UV-Vis, MS, XRD, TGA, and CV. 2. Complexes will be integrated at interfaces via pre-, co-, and post-deposition methods. 3. Surface and interfacial features will be analyzed using AFM, SEM, GIWAXS, XPS, and UPS. 4. Devices will be fabricated and evaluated for PCE, Voc, Jsc, FF, and EQE. 5. Stability will be assessed under humidity, heat, and illumination stress. 6. Charge transport and defect density will be examined via PL, TRPL, EIS, and SCLC. 7. DFT simulations will be performed to model interfacial binding and energy alignment.