Record High Efficiency Single-Walled Carbon Nanotube/Silicon p–n Junction Solar Cells

Abstract

Carrier transport characteristics in high-efficiency single-walled carbon nanotubes (SWNTs)/silicon (Si) hybrid solar cells are presented. The solar cells were fabricated by depositing intrinsic p-type SWNT thin-films on n-type Si wafers without involving any high-temperature process for p-n junction formation. The optimized cells showed a device ideality factor close to unity and a record-high power-conversion-efficiency of >11%. By investigating the dark forward current density characteristics with varying temperature, we have identified that the temperature-dependent current rectification originates from the thermally activated band-to-band transition of carriers in Si, and the role of the SWNT thin films is to establish a built-in potential for carrier separation/collection. We have also established that the dominant carrier transport mechanism is diffusion, with minimal interface recombination. This is further supported by the observation of a long minority carrier lifetime of ~34 μs, determined by the transient recovery method. This study suggests that these hybrid solar cells operate in the same manner as single crystalline p-n homojunction Si solar cells.

Carbon nanotubes for organic/inorganic hybrid solar cells

“…The hypothesis, supported by transmission spectroscopy analysis, is that after the HNO 3 purification process, the salts of the form [86]. A strong and stable doping of CNTs has been demonstrated [87] using MoO x thin layers with a thickness less than 10 nm.…”

Hybrid Materials for Integrated Photonics

“…In the field of photovoltaics, promising devices were recently proposed using the properties of innovating materials like carbon nanotubes, with really encouraging results [95][96][97]. These devices benefit from the superior optoelectronic properties of carbon nanotubes coupled with the well-developed technologies in the field of silicon photovoltaics.…”

“…These devices benefit from the superior optoelectronic properties of carbon nanotubes coupled with the well-developed technologies in the field of silicon photovoltaics. Using such approach, devices with power-conversion efficiency up to 11% were recently demonstrated [97].…”

Split gate and asymmetric contact carbon nanotube optical devices

“…CNTs also offer potential advantages in photovoltaic applications, since the bandgap of a CNT is directly related to its chiral angle and diameter [12] and can be chosen to match a wide range of the solar spectrum [13]. Recently, efficiencies of >11% have been demonstrated in p-type CNT/ n-type Si hetrojunction solar cells [14] and 14% in nitric acid wetted CNT/Si hetrojunction solar cells [15]. CNT based photodetectors may also have the ability to support multiple exciton generation which could drastically improve power conversion efficiencies [16].…”