Modeling of High-Efficiency Multi-Junction Polymer and Hybrid Solar Cells to Absorb Infrared Light

An Investigation of the Inverted Structure of a PBDB:T/PZT:C1-Based Polymer Solar Cell

Based on experimental results, this theoretical study presents a new approach for investigating polymers' solar cells. P-type PZT:C1 and N-type PBDB:T were used to construct a blend for use as a photoactive layer for the proposed all-polymer solar cell. Initially, an architecture of an ITO/PEDOT:PSS/PBDB:T/PZT:C1/PFN-Br/Ag all-polymer solar device calibrated with experimental results achieved a PCE of 14.91%. A novel inverted architecture of the same solar device, proposed for the first time in this paper, achieved a superior PCE of 19.92%. Furthermore, the optimization of the doping of the transport layers is proposed in this paper. Moreover, the defect density and the thickness of the polymer are studied, and a PCE of 22.67% was achieved by the optimized cell, which is one of the highest PCEs of polymer solar devices. Finally, the optimized polymer solar cell showed good stability amidst temperature variations. This theoretical study sheds light on the inverted structure of all-polymer solar devices.

Device Modeling of Efficient PBDB-T:PZT-Based All-Polymer Solar Cell: Role of Band Alignment

In this study, we present some design suggestions for all-polymer solar cells by utilizing device simulation. The polymer solar cell under investigation is formed by a photoactive film of a blend comprising PBDB-T as a polymer donor and PZT as a polymerized small molecule acceptor. The initial cell is based on a fabricated cell whose structure is ITO/PEDOT:PSS/PBDB-T:PZT/PFN-Br/Ag, which has a power conversion efficiency (PCE) of about 14.9%. A calibration procedure is then performed by comparing the simulation results with experimental data to confirm the simulation models, and the material parameters, implemented in the SCAPS (Solar Cell Capacitance Simulator) simulator. To boost the open circuit voltage, we investigate a group of hole transport layer (HTL) materials. An HTL of CuI or P3HT, that may replace the PEDOT:PSS, results in a PCE of higher than 20%. However, this enhanced efficiency results in a minor S-shape curve in the current density-voltage (J-V) characteristic. So, to suppress the possibility of the appearance of an S-curve, we propose a double HTL structure, for which the simulation shows a higher PCE with a suppressed kink phenomenon due to the proper band alignment. Moreover, the designed cell is investigated when subjected to a low light intensity, and the cell shows a good performance, signifying the cell's suitability for indoor applications. The results of this simulation study can add to the potential development of highly efficient all-polymer solar cells.

Efficient, Stable, and Low-Cost PbS Quantum Dot Solar Cells with Cr-Ag Electrodes

PbS quantum dots (QDs) are a promising nanostructured material for solar cells. However, limited works have been done to explore the active layer thickness, layer deposition techniques, stability improvement, and cost reduction for PbS QD solar cells. We address those issues of device fabrication herein and suggest their possible solutions. In our work, to get the maximum current density from a PbS QD solar cell, we estimated the optimized active layer thickness using Matlab simulation. After that, we fabricated a high-performance and low-cost QD photovoltaic (PV) device with the simulated optimized active layer thickness. We implemented this low-cost device using a 10 mg/mL PbS concentration. Here, spin coating and drop-cast layer deposition methods were used and compared. We found that the device prepared by the spin coating method was more efficient than that by the drop cast method. The spin-coated PbS QD solar cell provided 6.5% power conversion efficiency (PCE) for the AM1.5 light spectrum. Besides this, we observed that Cr (chromium) interfaced with the Ag (Cr–Ag) electrode can provide a highly air-stable electrode.

Extended 2,2'-Bipyrroles: New Monomers for Conjugated Polymers with Tailored Processability

The synthesis of 2,2′-bipyrroles substituted at positions 5,5′ with pyrrolyl, N-methyl-pyrrolyl and thienyl groups and their application in the preparation of conducting polymers is reported herein. The preparation of these monomers consisted of two synthetic steps from a functionalized 2,2′-bipyrrole: Bromination of the corresponding 2,2′-bipyrrole followed by Suzuki or Stille couplings. These monomers display low oxidation potential compared to pyrrole because of the extended length of their conjugation pathway. The resulting monomers can be polymerized through oxidative/electropolymerization. Electrical conductivity and electrochromic properties of the electrodeposited polymeric films were evaluated using 4-point probe measurements and cyclic voltammetry to evaluate their applicability in electronics.