Stable and Colorful Perovskite Solar Cells Using a Nonperiodic SiO₂/TiO₂ Multi-Nanolayer Filter

Abstract

While research on building-integrated photovoltaics (BIPVs) has mainly focused on power-generating window applications, the utilization of other underutilized surface areas in buildings, including exteriors, facades, and rooftops, has still not been fully explored. The most important requirements for BIPVs are color, power conversion efficiency (PCE), and long-term stability. In this work, we achieved colorful (red, green, blue, RGB) perovskite solar cells (PSCs) with minimized PCE loss (<10%) and enhanced photostability by exploiting the optical properties of nonperiodic multi-nanolayer, narrow-bandwidth reflective filters (NBRFs). The NBRFs were fabricated by multilayering high-index TiO2/low-index SiO2 in a nonperiodic manner, which allowed devices to demonstrate various colors with effectively suppressed unwanted baseline ripple-shape reflectance. The PCEs of PSCs with nonperiodic RGB-NBRFs were 18.0%, 18.6%, and 18.9%, which represent reductions of only 10%, 7%, and 6% of PCE values, respectively, compared to a black control PSC (20.1%). Moreover, the photostability of the PSCs was substantially improved by using the NBRFs because of ultraviolet blocking in the TiO2 layers. The G-PSC retained 65% of the initial PCE after 60 h of continuous illumination (AM 1.5G one sun) at the maximum power point, whereas the black PSC retained only 30%. Aesthetic color value, low PCE loss, and enhanced photostability of PSCs were simultaneously achieved by employing our NBRFs, making this a promising strategy with potential applicability in power-generating building exteriors.

Recent Advances in Perovskite‐Based Building‐Integrated Photovoltaics

“…Very recently, highly efficient colorful (red, green, blue) PSCs were fabricated by Yoo et al [ 21 ] who prepared narrow‐band‐width reflective filters (NBRFs) by stacking many alternating layers of high‐index TiO 2 and low‐index SiO 2 in a nonperiodic manner. By exploiting the optical properties of these multilayered NBRFs, PSCs with red, green, and blue colors exhibited PCEs of 18%, 18.6%, and 18.9%, respectively, while the black control PSC had an efficiency of 20.1%.…”

“…Image for colorful PSCs: Reproduced with permission. [ 21 ] Copyright 2019, American Chemical Society. Image for flexible PSC: Reproduced with permission.…”

“…[ 16–19 ] A more recent review, highlighting the current advances, was conducted by Shi et al [ 20 ] Colorful PSCs are an attractive type of BIPV that show promising applicability to building walls, fences, and parking roofs. [ 21 ] A more challenging type of BIPV combines the solar harvesting function with an electrochromic layer, forming dual‐function photovoltachromic cells (PVCCs). [ 22–27 ] The same combination can be used for thermochromic and light‐harvesting materials to yield a thermochromic solar cell.…”

Recent Progress on Advanced Optical Structures for Emerging Photovoltaics and Photodetectors

“…As shown in Figure 5d, Yoo et al used alternating high‐index TiO 2 /low‐index SiO 2 multilayer structures to create narrow‐bandwidth reflective filters on the substrate, obtaining red, green, and blue PSCs with PCEs of up to 18.9%. [ 127 ] Compared with typical DBRs that feature periodic structures, the nonperiodic structures they exploited eliminated the baseline ripple‐shaped patterns in the reflectance spectra (arising from the secondary constructive interference and widening the color gamut). The shape of the reflectance spectra of the reflective filters became more rectangular as the number of stacked layers increased, whereas the peak wavelength of the reflective filters moved to longer wavelength as the thickness of each multilayer increased.…”

Mitigating Potential-Induced Degradation (PID) Using SiO2 ARC Layer

“…Enhance the stability of the solar cell structure, because there will be a limited leakage of the current at the top layer (SiNx), preventing mismatched conditions of the solar cell, particularly during the PID test [26].  As there will be a limited leakage of the current, the expected drop in efficiency will also be at a minimum level.…”