Silicon Heterojunction Solar Cells with Nanocrystalline Silicon Oxide Emitter for Achieving High Fill Factor.

Wang, Qi; Yuhan, Cui; Liu, Fengzhen; Liu, Dongsheng; Sun, Zongheng; Dong, Gangqiang; Huang, Junming; Zhou, Yuqin et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Emitter and transparent conductive oxide (TCO) films are the critical functional layers of extremely promising silicon heterojunction (SHJ) solar cells. Here, p-type nanocrystalline silicon oxide (nc-SiO<sub><i>x</i></sub>:H(p<sup>+</sup>)) are employed as the emitter, replacing the widely used nanocrystalline silicon. The nc-SiO<sub><i>x</i></sub>:H shows a mixed-phase structural characteristic of nanocrystalline silicon grains and amorphous silicon oxide, in which the former spans the whole emitter, facilitating the carrier collection. A variety of TCO films, including Ce, Sn, or Hf doped and undoped indium oxides, are optimized for the nc-SiO<sub><i>x</i></sub>:H(p<sup>+</sup>) emitter. Film quality, work function, and bandgap states of the TCO films affect the contact resistivity of TCO/nc-SiO<sub><i>x</i></sub>:H(p<sup>+</sup>) and the solar cell performance. Using Ce doped indium oxide (ICO) with high mobility and certain bandgap states as the TCO layers, an efficiency of 26.29% and a high fill factor (FF) of 86.21% are achieved on the champion bifacial SHJ solar cells.