Electronic structure of a polymer nanowire on H-terminated Si(100)

Abstract

We measured current–voltage (I–V) characteristics of individual conducting polymers, poly(3-hexylthiophene)s (P3HTs), fixed on hydrogen-terminated Si(100) using scanning tunneling microscopy (STM)∕spectroscopy. The I–V curves reveal rectification characteristics that are attributed to the shift of the energy level of the valence-band maximum of P3HT under bias. The current suppression at positive substrate bias results from the effect of differential charging of the polymer between the opposite bias polarities, indicating the possibility for doping of polymer nanowires by using a STM tip as a gate electrode.

Progress on a Photovoltaic Cell Design Consisting of Silicon Nanowires and Poly (3‐ hexylthiophene)

“…The use of xylene for the dissolution of P3HT has been shown to produce higher efficiencies in polymer based PV cells than the use of chlorobenzene or chloroform [32,62]. However, the P3HT did not dissolve completely in the xylene, and since evaporation under a controlled atmosphere has produced well ordered thin films with low concentrations of impurities [10,63], this method is worth pursuing with other solvents.…”

“…SiNWs could potentially be considerably cheaper to produce than either c-Si or a-Si while retaining the capacity for high degrees of crystallinity and purity. P3HT has been shown to absorb more of the optical spectrum than other polymer semiconductors [2,19,[28][29][30]32,33] and has the highest reported mobility [15,29,31]. P3HT also offers the advantage of a variety of wet processing methods which are easily upgradeable to large scale production [19].…”

“…The nanowires would be anchored onto a more heavily doped substrate of n-type c-Si. [18,19,28,30,32,33] , the For this PV band gap of the Si [34], and the work functions of the two electrodes [35]. cell, both the SiNWs and the P3HT ould act as absorbers and carrier transporters [36].…”

“…The E OG s of the P3AT thin films are heavily dependent on morphology, but are typically around 2.0 eV [18,19,28,30,32,33] 6 . This is a bit narrow compared to the optical spectrum and can lead to a low I SC [18,19,39,51] unless compensated for by either increasing the thickness of the film, incorporating lower E OG materials, or introducing light trapping geometries [19].…”

“…Due to the improved stacking of the molecules [18,31,32], regioregular P3HT would be preferable [56,57] with reported mobilities between ~10 -4 to 0.1 cm 2 V -1 s -1 [29,58]. The degree of crystallininty in P3HT thin films may be controlled with the processing conditions (e.g.…”