Search Results (2)

In this study, we explored the potential of exfoliated transition metal dichalcogenides (TMDs) as innovative spray-coated hole transport layers (HTLs) in organic photovoltaics (OPVs), addressing the need for efficient and stable materials in solar cell technology. This research was motivated by the need for alternative HTLs that can offer enhanced performance under varying lighting conditions, particularly in indoor environments. Employing UV-visible absorption and Raman spectroscopy, we characterized the optical properties of MoS₂, MoSe₂, WS₂, and WSe₂, confirming their distinct excitonic transitions and direct bandgap features. The nanocrystalline nature of these TMDs, revealed through XRD patterns and crystallite size estimation using the Scherrer method, significantly contributes to their enhanced physical properties and operational efficiency as HTLs in OPVs. These TMDs were then integrated into OPV devices and evaluated under standard solar and indoor lighting conditions, to assess their effectiveness as HTLs. The results demonstrated that MoS₂, in particular, displayed remarkable performance, rivalling traditional HTL materials like MoO₃. It maintained high power conversion efficiency across a spectrum of light intensities, illustrating its versatility for both outdoor and indoor applications. Additionally, MoS₂ showed superior stability over extended periods, suggesting its potential for long-term usage in OPVs. This study contributes significantly to the field of photovoltaic materials, presenting TMDs, especially MoS₂, as promising candidates for efficient and stable OPVs in diverse lighting conditions, thereby broadening the scope of solar cell applications. Full article

Indoor organic photovoltaics (IOPVs) have attained considerable research attention as a power source for a low-power consumption self-sustainable electronic device for Internet of Things (IoT) applications. This study aims to develop an efficient cathode interfacial layer (CIL) based on a polyethyleneimine (PEIE) derivative, processed at room temperature, for the advancement of non-fullerene acceptor (NFA)-based IOPVs. Using a simple chemical reaction between polyethyleneimine and cobalt (II) chloride, we developed a 3D network-structured CIL. Through quaternary ammonium salts and chelating, metal ions act as mediators and induce metal-ion doping. An inverted device architecture with wide-bandgap and low-bandgap photo-absorber layer is utilized to understand the role of CILs under standard 1 sun and low-light or indoor light illuminations. The IOPV devices with modified CIL (Co-PEIE) having PBDB-T: IT-M and PBDB-T-2F: BTP-4F photo-absorber layers demonstrate a power conversion efficiency of 22.60% and 18.34% under 1000 lux LED lamp (2700 K) illumination conditions, respectively, whereas the IOPV devices with pristine PEIE CIL realized a poor device performance of 18.31% and 14.32% for the PBDB-T: IT-M and PBDB-T-2F: BTP-4F active layers, respectively. The poor device performance of PEIE interlayer-based IOPV under low-light conditions is the result of the significantly high leakage current and low shunt resistance that directly affect the open-circuit voltage (V_OC) and fill factor (FF). Therefore, the adjustable energy barrier and notably low leakage current exhibited by the Co-PEIE CIL have a crucial impact on mitigating losses in V_OC and FF when operating under low-light conditions. Full article