Photodetectors and photovoltaics based on semiconductor nanocrystals
A composite material is described. The composite material comprises semiconductor nanocrystals, and organic molecules that passivate the surfaces of the semiconductor nanocrystals. One or more properties of the organic molecules facilitate the transfer of charge between the semiconductor nanocrystals. A semiconductor material is described that comprises p-type semiconductor material including semiconductor nanocrystals. At least one property of the semiconductor material results in a mobility of electrons in the semiconductor material being greater than or equal to a mobility of holes. A semiconductor material is described that comprises n-type semiconductor material including semiconductor nanocrystals. At least one property of the semiconductor material results in a mobility of holes in the semiconductor material being greater than or equal to a mobility of electrons.
1. A composite material comprising:
semiconductor nanocrystals; and
organic molecules to passivate the surfaces of the semiconductor nanocrystals, the organic molecules further to facilitate a transfer of charge between the semiconductor nanocrystals, the organic molecules further to crosslink a resultant composite material and thereby increase a volume density of the semiconductor nanocrystals within the resultant composite material and increase a stability of the resultant composite material in time.
2. The composite material of claim 1 , wherein a crosslinking action is achieved by having at least some organic molecules bridge adjacent semiconductor nanocrystals.
3. The composite material of claim 1 , wherein the organic molecules include a first end group and a second end group.
4. The composite material of claim 1 , wherein the organic molecules include at least a conjugated moiety, a first end group coupled to the conjugated moiety, and a second end group coupled to the conjugated moiety.
5. The composite material of claim 1 , wherein the organic molecules include at least one organic compound chosen from a list of organic compounds including benzenedithiol, dibenzenedithiol, mercaptobenzoic acid, dicarboxybenzene, benzenediamine, and dibenzenediamine.
6. The composite material of claim 1 , wherein the semiconductor nanocrystals include at least one compound chosen from a list of compounds including PbS, PbSe, PbTe, CdS, CdSe, CdTe, SnS, SnSe, SnTe, Si, GaAs, Bi 2 S 3 , Bi 2 Se 3 , CuInS 2 , CuInSe 2 , Cu(InGa)Se 2 (CIGS), and CuGaSe 2 .
7. The composite material of claim 1 , wherein at least one end functional group passivates the semiconductor nanoparticle surfaces robustly in the solid state and avoids reactivity with adjacent metal contacts.
8. The composite material of claim 1 , wherein photoexcited charge carriers freely diffuse over a distance exceeding 50 nm in the resultant composite material.
9. The composite material of claim 1 , wherein the resultant composite material, when contacted to a metal having work function shallower than −4.5 eV, forms a Schottky contact.
10. The composite material of claim 1 , wherein organic molecules provide efficient hole transport.
11. The composite material of claim 1 , wherein the resultant composite material provides simultaneous electron transport and hole transport.