PbS / CdS Heterojunction Pn Junction Quantum Dot Sensitized Solar Cell Research Doping

Quantum dot sensitized solar cell （QDSC） has always been a focus of attention inthe studies of solar energy, because have high theoretical energy conversion efficiency（ECF）. However, the actual ECF is not ideal. In this regard, we used successive ioniclayer adsorption and reaction method （SILAR method） to incorporate dopant intoquantum dot （QD）. The main research content has three achievements:First, PbS:Bi/CdS or PbS:Ag/CdS sensitizers were prepared. The Bi entered thecube space of PbS to form gap doped as the Bi³⁺. This makes the lattice contract; thesize of QD decrease and the optical bandgap broaden. Bi³⁺is a donor, then impuritylevel makes light harvest of PbS:Bi increase in the near-infrared region. When Bi:Cd（molar ratio） is1:300in the solid film, defects introduced by dopant are the least. TheAg replaced Pb²⁺to form replacement doped as the Ag¹⁺. So lattice, size of QD andoptical bandgap keep basically unchanged. Ag¹⁺is a receptor, then impurity levelmakes liht harvest of PbS:Ag increase in the near-infrared region. When Bi:Cd is1:1.5in the solid film, defects introduced by Ag dopant are the least. The ECF of thedoped two QDSCs is both higher than undoped ones.Then, PbS/CdS:Bi and PbS/CdS:Ag sensitizers were prepared. The Bi³⁺enteredthe cube space of CdS to form gap doped. This makes the lattice expand; the size ofQD increase and the optical bandgap narrow down. Bi³⁺is a receptor, then impuritylevel makes light harvest of CdS:Bi red-shift in the visible region. When Bi:Cdis1:404in the solid film, defects are the least. While Ag¹⁺replaced Cd²⁺of CdS toform replacement doped. This makes the lattice expand; the size of QD increase andthe optical bandgap narrow down. Ag¹⁺is a receptor, then impurity level makes lightharvest of CdS:Bi red-shift in the visible region,but Ag impurity will shield PbSharvest visible light. So, the ECF of PbS/CdS:Bi QDSCs is higher; but the ECF ofPbS/CdS:Ag is very low.At last, Na2TeO3was dissolved in precursor solution of S2-of CdS to prepareCdS_xTe_1-xQD. The valence of Te in CdS_xTe_1-xis-2, the CdS_xTe_1-xis n type. With theincrease of Te content, the bandgap of CdS_xTe_1-xdecreases and are narrower than oneof CdS. When Na2TeO3:Na2S was1:20in the precursor solution, the CdS_xTe_1-xwouldbe the CdS0.9Te0.1. The short-circuit current density of CdS_xTe_1-xQDSC is nearly twotimes more than the CdS QDSC, the open circuit voltage is slightly higher than theCdS QDSC and the energy conversion efficiency of the cell is improved obviously.