Controlled Doping of Carbon Nanotubes with Metallocenes for Application in Hybrid Carbon Nanotube/Si Solar Cells

Abstract

There is considerable interest in the controlled p-type and n-type doping of carbon nanotubes (CNT) for use in a range of important electronics applications, including the development of hybrid CNT/silicon (Si) photovoltaic devices. Here, we demonstrate that easy to handle metallocenes and related complexes can be used to both p-type and n-type dope single-walled carbon nanotube (SWNT) thin films, using a simple spin coating process. We report n-SWNT/p-Si photovoltaic devices that are >450 times more efficient than the best solar cells of this type currently reported and show that the performance of both our n-SWNT/p-Si and p-SWNT/n-Si devices is related to the doping level of the SWNT. Furthermore, we establish that the electronic structure of the metallocene or related molecule can be correlated to the doping level of the SWNT, which may provide the foundation for controlled doping of SWNT thin films in the future.

Air‐tolerant Fabrication and Enhanced Thermoelectric Performance of n‐Type Single‐walled Carbon Nanotubes Encapsulating 1,1′‐Bis(diphenylphosphino)ferrocene

“…[15,16] Pristine SWNTst ypicallys how p-type characteristics, [17] and their n-type counterparts have been prepared by reactingt hem with electron donor compounds via solutionm ixing, casting and vapor deposition in inert atmosphere.H owever,i ti sw ell-recognized that most n-type SWNTsa nd efficient n-type doping reagents such as alkali metals and amines are generally unstablei na ir, preventing the fabricationa ir-stable bipolar electronic devices and modules. [18][19][20][21] Nakashimae ta l. have recently reported the encapsulationo fatypical n-type molecular dopant,c obaltocene, into SWNTs, whichsubsequently showed air stability relatively higher than the correspondings imple mixture. [21] For further practical use, it is important to stabilizea ll the components including n-type SWNTsa nd n-type dopants after doping, that is, positively-charged species.…”

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

“…Carbon nanotubes with cylinder-like, one-dimensional structures have attracted much interest for photovoltaic applications because of their electronic and optical properties [8][9][10][11] , including the ability to tune their band gaps over a wide wavelength range 12 , high carrier mobilities along their one-dimensional axes 13,14 and high optical transparency values with low resistivity 15 . Indeed, a variety of photovoltaic devices using carbon nanotubes such as carbon nanotube-based organic solar cells 16 , photoelectrochemical cells 17 , dye-sensitized solar cells 18 and carbon nanotube/Si solar cells 19,20 have been reported. Furthermore, the importance of carbon nanotubes as photovoltaic materials is continually increasing.…”

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells

“…Remarkably, these findings suggest that SWNT/Si hybrid solar cells could reach the PCE of Si p–n junction solar cells through optimized assembly of the interface . We have also shown that the analog system, n‐type SWNT thin films with bulk p‐type Si wafers, can approach the same efficiencies using small molecules or processes that ensure that O 2 is successfully removed from the SWNTs . Potential advantages of these hybrid approaches include the precise thickness control of the SWNT thin films and the room‐temperature fabrication of p–n junctions at the SWNT/Si interface .…”