Inhibiting Interfacial Charge Recombination for Boosting Power Conversion Efficiency in CdSe{Au} Nanohybrid Sensitized Solar Cell

Abstract

To boost the power conversion efficiency (PCE) of quantum dot solar cell (QDSC) by long-lived charge separated state, we are introducing CdSe{Au} nanohybrid material (NHM) which acts as a better light harvester than CdSe quantum dot (QD) alone. Steady state absorption studies show broadening of the absorption band of CdSe{Au} NHM up to 800 nm. The steady state and time-resolved luminescence studies reveal ultrafast electron transfer from CdSe QD to Au nanoparticles (NPs), forming a charge separated state. The measured PCE of the CdSe{Au} NHM is 4.39% which is significantly higher than pure CdSe QDs (3.37%). The enhancement of PCE has been explained by femtosecond transient absorption (TA) and electrochemical impedance spectroscopy (EIS). The ultrafast TA studies suggest subpicosecond electron transfer from CdSe QDs to Au NP and slower charge recombination in NHM. Interestingly 3 times higher recombination resistance at the interface of TiO 2 −CdSe{Au} as compared to TiO 2 −CdSe is shown by EIS measurements, which has also explained the enhancement of PCE for the NHM. To the best of our knowledge this is the first report of PCE for any kind of metal−semiconductor NHM.

Improving the Power‐Conversion Efficiency through Alloying in Common Anion CdZnX (X=S, Se) Nanocrystal Sensitized Solar Cells

“…In our continuous effort to correlate carrier dynamics with PCE we have employed TA spectroscopy to monitor the carrier relaxation and recombination dynamics in ultrafast time scale for several nanocrystal systems such as CdSeS, CdZnSSe alloy structures, CdSe/CdS core/shell structures and AuÀ CdSe heterostructures. [28,29,31,39,60,61] We have demonstrated how the charge carrier dynamics of intrinsic NC as well as at the NC/electrode interface gets affected by structural variation within the NC. Our conclusion was alloy NCs are superior candidates for QDSC due to their trap free nature and possibility of slower electron cooling.…”

Experimental and Theoretical Study into Interface Structure and Band Alignment of the Cu2Zn1–xCdxSnS4 Heterointerface for Photovoltaic Applications

“…The performance of polycrystalline PV cells can be significantly influenced by charge carrier dynamics and grain boundary engineering, − hence their deep understanding in Cu-based quaternary chalcogenides will assist future optimization of PV devices to achieve improved performance. In earlier investigations, − we have reported a direct correlation between efficiency and carrier dynamics in solar cells. Solar device performance can be significantly enhanced with elongated charge-carrier lifetimes when the grain size is increased from a few hundred nanometers to the micrometer level .…”

Quantum dot-sensitized solar cells

“…Meanwhile, metal−semiconductor nanohybrid materials (NHMs) were also used in enhancing light harvesting capability and photovoltaic performance of the resulting cells by Ghosh and coworkers. 328 Experimental results showed that the absorption onset of CdSe/Au can be red-shifted to 800 nm. Higher recombination resistance and longer electron lifetime were also confirmed by EIS measurements at TiO2−CdSe/Au interface in comparison with TiO2−CdSe.…”