Silicon Clathrate Films for Photovoltaic Applications

Abstract

Silicon clathrates are allotropes of silicon that show great promises for optoelectronics and batteries.However silicon clathrates in the form of films are relatively new and devices based on this material still have to be engineered. In this work we present a protocol for silicon clathrates film fabrication that does not necessitate a glove box. We show that dense films can be obtained with a pressure annealing treatment and that the films can be measured by atomic force microscopy. Ion implantation of P, B and As is performed on the clathrate films. Early photovoltaic devices are presented, with a maximum short circuit current density of 0.11 mA/cm².

Structural Origin of Reversible Li Insertion in Guest‐Free, Type‐II Silicon Clathrates

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Tetrel (Tt ¼ Si, Ge, Sn) clathrates are host-guest materials comprising cage frameworks of Tt elements that encapsulate alkali metal and alkaline earth metal guest atoms. Well known as promising candidates for thermoelectric materials, [1] clathrates also have interesting properties for optoelectronics [2][3][4] and superconducting [5][6][7] applications. Due to the large interest in Tt elements as high-capacity Li-ion battery anodes, the electrochemical properties of Tt clathrates have also been investigated in recent years, revealing properties distinct from those of diamond cubic structured analogues.

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Synthesis and characterization of silicon clathrates of type I Na8Si46 and type II NaxSi136 by thermal decomposition

“…Nothing is known about the origin of the photocarriers that are observed. While early solar cells based on Si-CL were proposed in previous studies [22,33], the low shortcircuit currents measured did not allow to measure external quantum efficiency EQE and therefore a doubt was present as to whether the photocarriers observed were generated by SiCL or by diamond Si impurities. In this way the optoelectronic properties of the films were further investigated using SPS.…”

“…Such film synthesis has been recently reported using the thermal decomposition pathway [21,[30][31][32][33][34]. The latter relies on a two-step process starting with the formation of a sodium silicide Zintl phase Na4Si4 by the reaction of silicon with sodium vapor, followed by the decomposition of this precursor into the desired SiCL type I (SiCL-I) and type II (SiCL-II) structure.…”

Evidence for “Unusual” Exchange–Correlation on Si(111) 7 × 7: Limitations of Density Functional Calculations for Charge Transfer Interactions on Semiconductor Surfaces

“…Similar allotropes also occur for Ge but are not as widely studied as Si or Sn, since the latter provide unusual properties. In the case of Si, these phases allow numerous applications for solar energy and power storage [ 148,149 ] while Sn exhibits unusual 2D quantum properties. [ 150–152 ]…”

“…Similar allotropes also occur for Ge but are not as widely studied as Si or Sn, since the latter provide unusual properties. In the case of Si, these phases allow numerous applications for solar energy and power storage [148,149] while Sn exhibits unusual 2D quantum properties. [150][151][152] These tetragonal Si or Sn allotropes have a higher density than in diamond, while the Si cage of the clathrate structures although more complicated, also have a higher density of Si atoms that form its cage.…”