Grain Boundary Engineering for Improved Thin Silicon Photovoltaics

Abstract

In photovoltaic devices, the bulk disorder introduced by grain boundaries (GBs) in polycrystalline silicon is generally considered to be detrimental to the physical stability and electronic transport of the bulk material. However, at the extremum of disorder, amorphous silicon is known to have a beneficially increased band gap, and enhanced optical absorption. This study is focused on understanding and utilizing the nature of the most commonly encountered Σ 3 GBs, to balance the incorporation the advantageous properties of amorphous silicon, while avoiding the degraded electronic transport * To whom correspondence should be addressed 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 of a fully amorphous system. A combination of theoretical methods is employed to understand the impact of Σ 3 GBs on the materials properties and full-device photovoltaic performance.

Interface structure prediction via CALYPSO method

“…Moreover, interfaces play a decisive role in determining the performance of many devices [3,4]. For instance, since the interfacial resistance between the electrode and electrolyte in all-solid-state lithium batteries is so substantial, it has become a bottleneck delaying further improvement of the battery performance [4], whereas silicon can exhibit improved photovoltaic performance owing to the presence of GBs [5]. Therefore, investigation of the effects of interfaces or GBs is of significant fundamental interest and practical importance [5,6].…”

Integrated structural reconstruction of unit structures of the meta-stable grain boundaries in diamond-structured materials presents first-order like phase transition.

“…Considering that fcc and bcc metals are mostly of metallic bonds, it is of interest to extend such studies into materials with different nature of chemical bonds, such as those with covalent bonds. One of the signi cant species with this aspect is the diamond-structured materials and their GBs also have notable effects on performances of many functional devices like solar cells and transistors [9][10][11] . Compared with fcc and bcc GBs, few reported studies have applied the term 'GB phases' on diamond-structured GBs though some properties related to phase behaviors have been discussed.…”

A tool for automatic recognition of [110] tilt grain boundaries in zincblende-type crystals

“…However, the performance of devices can also be improved by controlling the type, orientation and frequency of occurrence as well as the distribution of the GBs present in the synthesized structures (Raghunathan et al, 2014). This kind of GB engineering (Watanabe, 1985(Watanabe, , 2011 allows one to optimize the properties of known materials and to design new ones with better physical characteristics such as opto-electronic performance.…”