Proceedings of the 14th Workshop on Quantum Solar Energy Conversion - (QUANTSOL 2002)
March 17-23, 2002, Rauris, Salzburg, Österreich

The spectral photosensitivity of the silicon-chlorophyllin heterojunction

Tynyshtykbaev Kurbangali B., Kenshinbaev Nurlan K., Ibraev Sultan S., Dautov Askar L., Manakow Timur S.

Department of Physics, Kazakh National Technical University
22 Satpaev str., Almaty, 480013, Kazakhstan

In a basis of creation of molecular devices biochips there is the idea of self-ordering macromolecules with use of a method of the biomolecules self-organization. A basic element of the molecular device should be the organized molecular ensemble representing upper-molecular formations, in which the initial molecules are connected among themselves definitely. Such ensembles form by changing concentration, ??, temperature, pressure and other parameters of reaction .This ensembles product by self-organization of some reacting components or the molecular layers by means of consecutive adsorption.
The molecular devices should have functionality to react on the external signals. The external signals play a role of the starting mechanism bringing in action a lot of the important processes. For performance of the basic functions the similar systems should have receivers for absorption of a signal and further use of its energy for conformational changes of molecular complexes.
The effect of storing in memory molecular structures can be realised using conformational transformation macrostructure under influence of a electrical field or light. The ensembles of biomolecules carry out consecutive reactions on the molecular level with the certain reproducibility and efficiency, that cannot be achieved by means of modern electronic technology.
On the initially it is perspective of researches modelling functional properties of biomolecules on the basis of their liquid crystal properties, which are sensitive to external influences and are controllable.
The research of the power and entropy parameters of processes of self-organization before made by us has shown a conducting role of the entropy factors in conformational changes processes [1,2].
Therefore it is necessary to know the conformational changes for controllable management of the molecular device. The conformational changes are caused by the entropy factors. It is difficult to find separately the conformational and dehydrated contributions to complete change of entropy.
For division conformational and dehydrated contributions we have determined complete entropy of aggregation of hydrocarbon molecules. It was made by representation of system water hydrocarbon as system of contacts.

dS = R ln  g h N

where R - universal gas constant, h - solubility hydrocarbon in water, N - quantity of evaporated water molecules, which experimentally can be find , g - constant.

This entropy change is connected with two effects
1) the conformational changes D Sconf and
2) the aggregation of molecules chlorophyllin during their dehydration, D Sdehydr

D S = D Scon + D Sdehydr.

Thus, for the first time we managed to divide conformational and dehydrated contributions to the entropy change and to show, that the entropy-managed process of self-ordering of chlorophyllin molecules in water is caused mainly by conformational transformations of structure of the chlorophyllin water solution [3,4].
We investigate spectral photosensitivity heterosystem of the solution chlorophyllin-silicon (picture). The broadening of heterojunction spectral photosensitivity to short-wave field is observed. This effect may be explained by the next factors. 1. Brightening properties of chlorophyllin because of by the decrease of silicon face reflection coefficient in short-wave field. 2. The recombination centers of silicon face are passivated by active groups of chlorophyllin molecules. 3. The quazi-zone structure is formed near to silicon face by short-range order of spatial position of chlorophyllin molecules. The chlorophyllin on silicon face might be taken in account as broadband gap semiconductor.

The spectral photosensitivity curve doesn't have the kink which characteristic to semiconductor heterojunction with different energy gaps. The heterojunction interface is non-defectives because of ability of the chlorophyllin molecules to repeat the orientation of the silicon matrix atoms.


  1. Tynyshtykbaev K.B., Kenshinbaev N. K. // Izv. National Science Academy of Republic of Kazakhstan. 2000. P. 61-64.
  2. Tynyshtykbaev K.B., Kenshinbaev N. K. // Izv. National Science Academy of Republic of Kazakhstan. 2001. P. 81-85.
  3. Tynyshtykbaev K.B., Kenshinbaev N. K., Dautov A.L. // Journal of Chemical Physics (Russia). In press.
  4. Tynyshtykbaev K.B., Kenshinbaev N. K. // Journal of Physical Chemistry (Russia). In press.


Last updated Januray 21, 2002