Charge carrier trapping processes in lanthanide doped La-, Gd-, Y-, and LuPO4

Charge carrier trapping processes in lanthanide doped La-, Gd-, Y-, and LuPO4

Lyu, T. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Dorenbos, P. (TU Delft RST/Fundamental Aspects of Materials and Energy)

2017-12-06

Various methods for deliberate design electron and hole trapping materials are explored with a study on double lanthanide doped rare earth ortho phosphates. Cerium acts as recombination center while lanthanide codopants as electron trapping centers in LaPO4:0.005Ce3+,0.005Ln3+. The electron trap depth generated by lanthanide codopants can be tailored by the choice of lanthanide, and for fixed set of lanthanide dopants like in Gd1-xLaxPO4:0.005Ce3+,0.005Ho3+ solid solutions by changing x leading to conduction band (CB) engineering. Here, the electrons liberated from Ho2+ recombine through the conduction band at Ce4+ to yield Ce3+ 5d-4f emission. In contrast, samarium, europium and ytterbium are recombination centers, while Tb3+ and Pr3+ act as hole trapping centers in double lanthanide doped YPO4. For Tb3+ and Pr3+ codopants recombination is realized via hole release rather than the more common reported electron release. The holes recombine via the valence band with the electrons trapped at Yb2+, Sm2+, or Eu2+ to generate 4f-4f luminescence from Yb3+, Sm3+, or Eu3+. Lu3+ was introduced in YPO4 to tailor the valence band (VB) energy and to tune the hole trap depths of Tb3+ and Pr3+ in Y1-xLuxPO4:0.005Ln3+ solid solutions. Our results promote the deliberate design electron and hole trapping materials from deep understanding of trap level locations and on the transport and trapping processes of charge carriers.

http://resolver.tudelft.nl/uuid:afce490f-a4f7-449c-9b4a-7154dce2c994

https://doi.org/10.1039/C7TC05221A

2018-12-08

2050-7526

Journal of Materials Chemistry C: materials for optical and electronic devices

Institutional Repository

journal article

© 2017 T. Lyu, P. Dorenbos