Homogenization of Optical Field in Nanocrystal-Embedded Perovskite Composites
Yu Hou, Jun Zhang, Xianlin Zheng, Yiqing Lu, Alexej Pogrebnyakov, Haodong Wu, Jungjin Yoon, Dong Yang, Luyao Zheng, Venkatraman Gopalan, Thomas M. Brown, James A. Piper, Kai Wang, Shashank Priya
Abstract
Photonic upconversion of in-band light into shorter-wavelength light has been proposed as a protocol to overcome the Shockley–Queisser (SQ) limit of photovoltaics. Many research contributions have attempted the incorporation of upconversion materials to realize this strategy. However, devising a real device with an efficiency exceeding the SQ limit still remains technically unreachable. To understand this paradoxical question, herein we use a typical upconversion nanoparticle (UCNP) with halide perovskite as a platform to quantify the UC contribution to the efficiency improvement. Our results show that the UC-induced photocurrent gain is negligible; nevertheless, the incorporation of nanomaterials even without UC capability can still enhance the photocurrent, which is related to a redistribution of the optical field and consequently a homogenization of the optical field (HOF). This can lead to a reduced photocarrier loss and provide a noticeable photocurrent enhancement (ca. 7%), which explains the general photocurrent improvement in solar cells with nanomaterials.