Ultraviolet responses of a heterojunction Si quantum dot solar cell

Abstract

We investigated the ultraviolet (UV) responses of a heterojunction Si quantum dot (QD) solar cell consisting of p-type Si-QDs fabricated on a n-type crystalline Si (p-Si-QD/n-c-Si HJSC). The UV responses were compared with a conventional n-type crystalline Si solar cell (n-c-Si SC). The external and internal quantum efficiency results of the p-Si-QD/n-c-Si HJSC exhibited a clear enhancement in the UV responses (300-400 nm), which was not observed in the n-c-Si SC. Based on the results of the cell reflectance and bias-dependent responses, we expect that almost all UV responses occur in the p-Si-QD layer, and the generated carriers can be transported via the Si-QD layer due to the formation of a sufficient electric filed. As a result, a high power conversion efficiency of 14.5% was achieved from the p-Si-QD/n-c-Si HJSC. By reducing the thickness of the n-Si substrate from 650 μm to 300 μm, more enhanced power conversion efficiency of 14.8% was obtained which is the highest value among the reported Si-QD based solar cells to date.

Recent Advancements in Applications of Graphene to Attain Next-Level Solar Cells

“…Proper band alignment increases the efficiency of SCs according to the band offset optimization proposed by Minemoto et al [178] and the concept of band offset uniqueness proposed in my previous paper [179]. Earlier designed metal TCE-based metal TCE/SQD SCs offered efficiency in the range of 10.4-14.8% [180][181][182][183][184]. A recent study on the utilization of graphene TCEs in graphene/SQDs:SiO 2 /Si heterojunction SC showed maximum efficiency of 16.2% [167].…”

Improvement of power conversion efficiency by a stepwise band-gap structure for silicon quantum dot solar cells

“…This is because both the stoichiometry of the SiO x layer and the relative thicknesses of the SiO x and SiO 2 layers must be precisely controlled at the same time [10,20]. In order to solve the difficulties of multilayer fabrication, a heterojunction solar cell with a single layer composed of nano sized Si-QDs was fabricated and the power conversion efficiency was improved to 14.8% [21]. Heterojunction Si-QD solar cells with a single layer improved its efficiency to 17.04% through optimization of the doping concentration and maximization of the Si-QD density [22].…”

High efficiency Si quantum dot heterojunction solar cells using a single SiOX:B layer

“…However, photoexcited carrier transport and the number of generated Si QDs in this structure is restricted by the adjacent SiO 2 layer, which has a crucial impact on the efficiency of Si QD based photovoltaic cells. [8,13] Recently, we have fabricated Si QD heterojunction solar cells with 14.8% efficiency from a boron-doped single SiO x layer (SiO x :B) [14]. In addition, we have studied the importance of the B doping concentration for effective electronic band engineering of the absorption layer in Si QD heterojunction solar cells [15].…”