Hybrid solar cells based on single-walled carbon nanotubes/Si heterojunctions

Abstract

Photovoltaic devices based on single-walled carbon nanotubes (SWNTs) and n-silicon heterojunctions have been fabricated by a spray deposition process. We provide direct evidence that nanotubes serve as an active photosensing material involved directly in the photon absorption process as well as contributing to charge separation, transport and collection. The characteristic band of the SWNT band in the photoconductivity spectrum matches the S(11) absorption band of semiconducting SWNTs of 7,6 chirality. Centrifugation of the SWNTs provides two fractions. The sediment fraction exhibits a conversion efficiency ( approximately 1.7%) higher by a factor of eight compared to the supernatant fraction. SEM images and conductivity measurements show that the SWNT network morphology of the sediment fraction has longer and thicker nanotube bundles forming highly porous films, accounting for the enhanced conductivity and higher transparency.

Self-Organized Micro-Honeycomb Network Structure of Single-Walled Carbon Nanotubes for Photovoltaic Devices

“…The photo-conversion mechanism has been argued whether it is p-n junction or Schottky junction. In order to explore this mechanism of SWNT/n-silicon, Kozawa et al used (6,5) enriched CoMoCAT on top and obtained the PCE of 2.4% [4]. Ong et al used SWNTs with (7,6) major chirality, and obtained the efficiency of 1.7% [5].…”

“…In order to explore this mechanism of SWNT/n-silicon, Kozawa et al used (6,5) enriched CoMoCAT on top and obtained the PCE of 2.4% [4]. Ong et al used SWNTs with (7,6) major chirality, and obtained the efficiency of 1.7% [5]. The same method was adopted by Jia et al [6], and PCE was only 1.5%.…”

Enhancement of Photocurrent Generation by C60-encapsulated Single-walled Carbon Nanotubes in Ru-sensitized Photoelectrochemical Cell

“…Carbon nanotubes (CNTs) have been attractive materials in application to photovoltaic (PV) energy conversion devices, 13,14 and induced a great deal of interest in the development of new generation of organic and hybrid solar cells. Several groups reported hybrid PV devices based on a CNT/n-type Si heterojunction.…”

Carbon Nanotube Hybrids for Renewable Energy

“…Interestingly, in majority PV studies of CNT hybrids, the role of CNTs in light harvesting was underestimated in the photocorversion process. Recent reports demonstrated that CNTs can be involved not only in charge separation and transport processes, but also in efficient light absorption [9][10][11][12][13][14]. It was a great hope in the beginning of 2000 th that an incorporation of carbon nanotubes in organic photovoltaic device (OPV) and formation of bulk heterojunction between CNT and polymer or small molecules should significantly improve solar cell performance and boost PCE level beyond of 10%.…”

“…For instance, very recently, a surprisingly high photoconversion efficiency (PCE) of ~14% for CNT/Si hybrid solar cells has been reported [7], exceeding any PCE for organic and hybrid photovoltaics. Noteworthy, research in the field of CNT/semiconductor PV is very new (just past five years) and limited by few groups [7][8][9][10] as compared with substantial efforts and time (about 20 years) spent by PV community in other directions such as polymer based and dye-synthesized solar cells where the best PCE is still in the range of 10-12% [11][12][13]. Photoactive CNT/ counterpart nanohybrids include significant diversity in the CNT morphology (network and individual CNTs), their structure (SWNTs and MWNTs) and electronic properties (semiconducting and metallic).…”