Enhancing the power conversion efficiency of SrTiO3/CdS/Bi2S3quantum dot based solar cell using phosphor

• Published in: Applied surface science Vol. 494; pp. 551 - 560
• Main Authors: Peter, I. John, Vignesh, G., Vijaya, Subbiah, Anandan, Sambandam, Ramachandran, K., Nithiananthi, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-11-2019
• Subjects: Cascaded heterostructure; Phosphorescence; Quantum dots; Solar cells; Tunneling; Cascaded heterostructure; Solar cells; Tunneling; Phosphorescence; Quantum dots
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.07.092

The role of down-conversion phosphorescence in the enhancement of power conversion efficiency (PCE) of TiO2: SrTiO3/CdS/Bi2S3/ZnS: Cu heterostructure solar cell is reported here. ZnS:Cu is used as phosphor which converts a fraction of the ultra violet energy to visible range, increasing the light harvesting capacity. Also this acts as a passivation layer, to reduce the charge recombination. SrTiO3 nanoparticles with spherical morphology were synthesized by co-precipitation technique and CdS, Bi2S3 and ZnS:Cu were grown on the SrTiO3 by successive ionic layer adsorption and reaction (SILAR) method after optimizing the Cu concentration. The structural, morphological and composition were studied by XRD, SEM, TEM and XPS measurements. J-V measurements of TiO2:SrTiO3/CdS/Bi2S3/ZnS:Cu3 structure based solar cell are done by solar simulator under 1.5 AM and found to exhibit an enhancement in PCE to the tune of 55% than SrTiO3/CdS/Bi2S3 (pristine) based solar cell. Incident Photon Current Efficiency (IPCE) spectrum covered a spectral range of 400 to 900 nm for TiO2:SrTiO3/CdS/Bi2S3/ZnS:Cu3 cell with the maximum IPCE ~51%. Electrochemical impedance analysis is also carried out in the form of Nyquist and Bode phase plots for the fabricated solar cells which possess low values of Rs, Rct and longer life time for the charge carriers which is favorable for higher PCE.
Owing to the phosphorescence-reabsorption, longer carrier life time and lower charge transfer resistance in TiO2:SrTiO3/CdS/Bi2S3/ZnS:Cu3 heterostructure based cell obtained 55% of efficiency enhancement compared to pristine cell (SrTiO3/CdS/Bi2S3). [Display omitted]
•TiO2:SrTiO3/CdS/Bi2S3/ZnS:Cu heterostructure solar cell is synthesized and analyzed.•Semiconducting QDs (quantum dots) are adsorbed on SrTiO3 by SILAR (successive ionic layer adsorption and reaction).•Phosphorescence, tunneling and longer lifetime enable enhancement of PCE (power conversion efficiency).•TiO2:SrTiO3/CdS/Bi2S3/ZnS:Cu3 cell has attained 55% of efficiency enhancement.