Improved color rendering index of low band gap semi-transparent polymer solar cells using one-dimensional photonic crystals

Abstract

Neutral color semitransparent polymer solar cells (STPSCs) have attracted wide attention due to their unique application on building integrated photovoltaic (BIPV) in recent years. Herein, we report a kind of low bandgap STPSCs with high color rendering index (CRI), which can be modulated by one-dimensional photonic crystals (1DPCs). To flat transmitted light and eliminate chromatic aberration, the 1DPCs were integrated on top of STPSCs as a wavelength-dependent filter. We design the centre wavelength of 1DPC as 520 nm to level the concavo-convex transmittance spectrum induced by the absorption of PSBTBT:PC60BM. By turning the pairs of 1DPCs, the optimal STPSCs with 3 pairs of 1DPC achieve an increased CRI from 77 to 91 under AM 1.5G illumination light source, a suppressed chromaticity difference (DC) from 0.0308 to 0.0045 and a enhanced power conversion efficiency(PCE) from 3.43 % to 4.01 % compared to devices without 1DPC. Furthermore, we believe that the new method of STPSCs incorporating with 1DPCs filters to balance the total transmittance spectrum and enhance the CRI will play a important role in future BIPV applications. Fig. 1 Device structure of STPSC with 1DPC.

Metal-nanostructures – a modern and powerful platform to create transparent electrodes for thin-film photovoltaics

“…The reader is kindly referred to a very recent review article on this particular topic by Chueh et al 230 In an attempt to control the color of semitransparent OSCs, top electrodes of WO 3 /Ag/1DPC were suggested, where 1DPC is a one-dimensional photonic crystal that consisted of [MoO 3 / LiF] #pairs or [WO 3 /LiF] #pairs . 231,232 The 1DPC relied on the large refractive index contrast between MoO 3 and LiF (2.11 and 1.44, respectively). The number of pairs (#pairs) in the 1DPC was varied between 1 and 5.…”

High-Efficiency and High-Color-Rendering-Index Semitransparent Polymer Solar Cells Induced by Photonic Crystals and Surface Plasmon Resonance

“…Recently, the power conversion efficiency (PCE) of single-junction PSCs has been reported as high as 12% with novel band gap polymer materials and optimized device structures, and the PCE of ST-PSCs with a nonfullerene acceptor has reached 9.77% . So far, although remarkable progress has been made in developing efficient ST-PSCs, the PCE of the most devices still lags far behind that of the state-of-the-art opaque ones. − It is expected that efficiency, transparency, and color characterization of ST-PSCs can be further improved by incorporating novel materials for active layers, transparent electrodes, and suitable device structure, which possess a tremendous application advantages in building-integrated photovoltaics and urban esthetics installation. − …”

Semitransparent Flexible Organic Solar Cells Employing Doped-Graphene Layers as Anode and Cathode Electrodes

“…Currently, various organic donor and acceptor compounds with different absorption bands are used to optimize the transmittance of an optical device in visible region. − Flexible organic solar cells (FOSCs) typically require small amount of active material, coupled with suitable substrates and electrodes, to provide an opportunity for realizing low-cost flexible and transparent energy harvesting. − To date, most organic solar cells (OSCs) consist of an organic layer sandwiched between an indium tin oxide (ITO) anode and a metal cathode and electron/hole transport layers (ETLs/HTLs). − Recently, many studies have been done for increasing the absorption of light transmitted through the ITO-based OSCs, − thereby enhancing their efficiency. Since ITO and metal electrodes are both disadvantageous in view of light transmittance, rigidity, and flexibility, they are not suitable for semitransparent FOSCs applications.…”