Band gap engineered ternary semiconductor Pb_xCd_1−xS: Nanoparticle‐sensitized solar cells with an efficiency of 8.5% under 1% sun—A combined theoretical and experimental study

Abstract

We report the synthesis and photovoltaic properties of a ternary metal sulfide alloyed semiconductor PbxCd1−xS prepared by the two‐stage sequential ionic layer adsorption reaction. The synthesized PbxCd1−xS nanoparticles (NPs) retain the hexagonal structure of the CdS host with Pb substituting a fraction of the Cd atom (x = 0‐0.17). Band structures of PbxCd1−xS with various Pb contents x were calculated using the complementary density functional theory (DFT) method. Optical, quantum efficiency, cyclic voltammetry measurements, and band structure calculation revealed that the band gap of PbxCd1−xS decreased with increasing x, resulting in an increased optical absorption band from 500 to 720 nm (1.73‐2.44 eV) for x = 0 to 0.17. Solid‐state PbxCd1−xS semiconductor nanoparticle‐sensitized solar cells (NSSCs) were fabricated from the synthesized NPs using spiro‐OMeTAD as the hole‐transporting material. The best Pb0.05Cd0.95S cell yielded a power conversion efficiency (PCE) of 3.67%, a Voc of 0.70 V, and a fill factor (FF) of 62.8% under 1 sun. The PCE increased to 5.93% under a reduced light intensity of 0.1 sun and further increased to 8.48% under 0.01 sun. The external quantum efficiency (EQE) spectrum covers the spectral range of 300 to 730 nm with a maximal EQE of 82% at λ = 580 nm. The PCE over 8% can be categorized into a high‐efficiency NSSCs. In addition, the Voc of 0.70 V is a relatively high Voc among all NSSCs. The high PCE and Voc suggest that PbxCd1−xS has potential to be an efficient solar absorber.

Cu-mediated broadening of the absorption band of quaternary Cu–Ag–In–S/CdSe type-II core/shell quantum dot-sensitized solar cells with an efficiency of 12.51% under 0.25 sun

“…For instance, Pb x Cd 1− x S solid-state QDSSCs improved PCE from 1.36% (CdS) to 3.67% after cation-alloying with Pb. 15 Yuan et al also achieved a similar PCE in liquid-junction Pb x Cd 1− x S QDSSCs. 16 In the case of the anion alloying approach, the creation of ternary alloyed CdS 1− x Se x resulted in a commendable PCE of 5.12%.…”

Rare-earth-incorporated ternary CexCd1−xS quantum dot-sensitized solar cells

“…This two-dipping process formed one SILAR cycle for Cd–S seeds. As reported in the literature, the optimal number of SILAR cycles for CdS had been determined to be seven; 18 hence, the number of CdS SILAR cycles was fixed at six herein to make room to accommodate the incorporated Ce in this work. Lastly, the double-layer Ce–S/Cd–S seeds were annealed at 250 °C for 10 min, forming ternary Ce x Cd 1− x S QDs.…”

Influence of strong electric field on the properties in semiconductor quantum dot

“…Their conductivity is more than that of the dielectrics but less than that of conductors [3]. Apart from electrical conductivity, SC materials have interesting physical and chemical properties and useful functionalities including narrow and intensive emission spectra, continuous absorption bands, high chemical and photo-bleaching stability, processability and surface functionalities [2] making them promising candidates for a wide range of applications in diverse disciplines such as solid state physics, inorganic chemistry, physical chemistry, colloid chemistry, materials science, and recently biological and medical sciences, engineering, and inter disciplinary fields [4][5][6][7][8][9][10].…”