No abstract

Tandem organic solar cells (OSCs) show great potential due to advantages such as the utilization of wide-spectrum light and low thermalization loss. The current mismatch between sub-cells is one of the major issues reducing the final output efficiency of a tandem device. In this paper, we focus on the current mismatch of tandem OSCs at oblique incidence and aim to reduce its adverse effect on the performances of realistic devices working at varying incident angle. Firstly, we propose an optical analysis method based on the 4×4 matrix formalism to analyze and optimize the performance of tandem solar cells at arbitrary incident angles. Compared with those optimal designs via matching the currents of sub-cells only at normal incidence, the proposed method chooses the optimal structure of the tandem device by maximizing the generated energy density per day with considering the current match at different incident angles during daytime. With the proposed method, a typical tandem organic solar cell is optimized as an example, and the optimized tandem device has a balanced current match at all incident angles during a whole day. Experimental results demonstrate that the generated energy density per day of the optimized tandem device has increased by 4.9% compared to the conventional device optimized only at normal incidence. The proposed method and results are expected to provide some new insights for the performance analysis and optimization of tandem or multi-junction solar cells, especially those devices exhibiting serious current mismatch between sub-cells at varying incident angles in practical applications.

Poor wide field-of-view (FOV) performances and low production yields are major factors that restrict the application of organic light-emitting diodes (OLEDs) in large-size panels. In this paper, we propose an optimization and analysis method to improve optical performances of stratified OLEDs over wide FOV with consideration of the thickness tolerance in the practical production process. With key optical performance parameters defined using the angle-dependent luminescence spectra, including the external quantum efficiency (EQE), current efficiency (CE), just noticeable color difference (JNCD), and the color coordinates, the optimization of OLEDs over wide FOV is described as a multi-parameter and multi-objective optimization problem which is accomplished by the genetic algorithms (GAs). Further, the thickness tolerance is introduced to improve the structure stability considering thickness fluctuations in the practical production process. Appropriate thickness tolerances can be determined to achieve stable structures for the OLED device by defining and analyzing the distributions of preference regions of the GA output noninferior solutions and the correlation coefficients between the layer thicknesses. Based on the proposed methods, high-throughput simulations are carried out on a typical Green Bottom-emitting OLED (G-BOLED) to design a stable device structure with high-performances. Experimental results demonstrate that compared with the initial device, the performances of the optimized device have been significantly improved, with the CE improved by over 30% in the normal direction, the EQE improved by over 20%, and the JNCD reduced from 4.45 to 1.36 over the whole FOV of 0-60°. In addition, within the thickness fluctuation in the practical process, optimized devices can strictly satisfy the “Best” preferred region, indicating that the structure is more stable against thickness fluctuations in the practical production process. The proposed optimization method can simultaneously improve optical performances over wide FOV and provide a stable structure for stratified OLEDs, and it therefore can be expected to improve the production yields and promote the OLEDs applied to large-size panels.

Triple patterning (TP) lithography becomes a feasible technology for manufacturing as the feature size further scale down to sub 14/10 nm. In TP, a layout is decomposed into three masks followed with exposures and etches/freezing processes respectively. Previous works mostly focus on layout decomposition with minimal conflicts and stitches simultaneously. However, since any existence of native conflict will result in layout re-design/modification and reperforming the time-consuming decomposition, the effective method that can be aware of native conflicts (NCs) in layout is desirable. In this paper, a bin-based library matching method is proposed for NCs detection and layout decomposition. First, a layout is divided into bins and the corresponding conflict graph in each bin is constructed. Then, we match the conflict graph in a prebuilt colored library, and as a result the NCs can be located and highlighted quickly.

The dipole orientation and distribution have significant influence on the performances of OLEDs, and they are prerequisites for the optical design and analysis of OLEDs. In this paper, based on the dipole radiation model for OLEDs, a two-step inversion method is proposed to accurately achieve dipole features simultaneously, including dipole orientation and distribution, in OLED devices, without knowing the approximate shape of the dipole distribution.