Synthesis, characterization and photovoltaic applications of a low band gap polymer based on s-tetrazine and dithienosilole.

A new copolymer of dithienosilole (DTS) and dithienyl-s-tetrazine (TTz), PDTSTTz, has been designed and synthesized. This solution processable polymer shows a low band gap, strong absorption and good thermal stability. Solar cells from the blend of this polymer with PC(71)BM showed power conversion efficiency (PCE) up to 4.

Ab initio constrained crystal-chemical Rietveld refinement of Ca10(VxP1-xO4)6F2 apatites.

Extraction of reliable bond distances and angles for Ca10(VxP1-xO4)6F2 apatites using standard Rietveld refinement with Cu Kalpha X-ray powder data was significantly impaired by large imprecision for the O-atom coordinates. An initial attempt to apply crystal-chemical Rietveld refinements to the same compounds was partly successful, and exposed the problematic determination of two oxygen-metal-oxygen angles. Ab initio modeling with VASP in space groups P6(3)/m, P2(1)/m and Pm showed that both these angular parameters exhibited a linear dependence with the vanadium content.

Geometrical parameterization of the crystal chemistry of P6(3)/m apatites: comparison with experimental data and ab initio results.

Experimental structure refinements and ab initio simulation results for 18 published, fully ordered P6(3)/m (A;{\rm I}_4)(A;{\rm II}_6)(BO4)6X2 apatite end-member compositions have been analyzed in terms of a geometric crystal-chemical model that allows the prediction of unit-cell parameters (a and c) and all atom coordinates. To an accuracy of +/- 0.025 A, the magnitude of c was reproduced from crystal-chemical parameters characterizing chains of .