Progress of Graphene–Silicon Heterojunction Photovoltaic Devices

Abstract

Solar cells fabricated with the most dominant material in industry, silicon (Si), developed rapidly in the recent years. Traditional Si solar cells require a complex process of fabricating junction. Thanks to its exotic electrical and optical properties, graphene (Gr) has attracted tremendous research interest in optoelectronic device applications, e.g., solar cells. The Gr/Si solar cell can be achieved by a simple room‐temperature transfer technique, which exhibits great potential application in photovoltaics. Currently, many researchers focus on the strategies to dope the Gr for the cell efficiency improvement, from 1.65% to 16.2%. Although great progress has been made, there are still some key issues to be solved on the way to the commercialization of Gr/Si solar cells. Here, the recent progress in the development of Gr/Si solar cells is comprehensively reviewed, and the road map of Gr/Si solar cell techniques in the future is discussed.

CVD Graphene on Textured Silicon: An Emerging Technologically Versatile Heterostructure for Energy and Detection Applications

“…Since graphene forms a Schottky junction or rectifying heterojunction on contact with the Si substrate, [ 5,6,27,28 ] the non‐linear J – V characteristic of the Schottky junction can be expressed by the thermionic model: or where, q is the electronic charge, k is the Boltzmann constant, J s is the reversed saturated current density and n is the diode ideality factor.…”

“…[ 34 ] The intentional and controlled doping of CVD‐graphene is required to reduce its large lateral resistivity so that its work function could be increased which thereby increases the Schottky barrier height (SBH), and eventually enhances the photovoltaic performance of the graphene/Si heterostructure based devices. [ 5,6,35 ] Similarly, 15.2% PCE was achieved by introducing MoS 2 interfacial layer between CVD‐graphene and n ‐type Si substrate to fabricate graphene/MoS 2/ Si heterostructure based solar cell, where MoS 2 interfacial layer served as a hole transporting layer/electron blocking layer to graphene and suppressed the charge recombination at graphene/Si interface as well. [ 33 ] Moreover, an anti‐reflection coating (ARC) of TiO 2 nanoparticles was spin‐coated on the surface of graphene to increase its light absorption capability.…”

“…[1][2][3] Graphene is well known for its unique structure and extraordinary properties such as robust in-plane intrinsic strength, high charge-carrier mobility, and relatively high optical transparency. [1,[4][5][6] Chemical vapor deposition (CVD) is considered as a reliable and superior technique to synthesize large area and high-quality graphene films on transition metals such as Cu and Ni. [7][8][9][10][11][12] Moreover, the CVD technique can also be used to synthesize polycrystalline as well as single crystalline graphene films on transition metals.…”

“…Graphene forms a Schottky junction or rectifying heterojunction on contact with the Si substrate. [5,6,27,28] The basal plane of a graphene film contacts the bulk or 3D Si and gives rise to a surface junction with an intrinsic driving potential to transport the electrons and holes across the 2D/3D junction. [5,6] Such a surface junction is also known as the photojunction because it is only one atom below the front surface, where graphene serves as both a light transparent top electrode and a charge-separating, transport-active layer.…”

“…[5,6,27,28] The basal plane of a graphene film contacts the bulk or 3D Si and gives rise to a surface junction with an intrinsic driving potential to transport the electrons and holes across the 2D/3D junction. [5,6] Such a surface junction is also known as the photojunction because it is only one atom below the front surface, where graphene serves as both a light transparent top electrode and a charge-separating, transport-active layer. [5,6,29] However, the light absorption capability of SLG is ≈2.3% only, which is not sufficient for light harvesting.…”