In-Situ Probing Plasmonic Energy Transfer in Cu(In, Ga)Se2 Solar Cells by Ultrabroadband Femtosecond Pump-Probe Spectroscopy.

Shih-Chen Chen,Atsushi Yabushita,Hao-Chung Kuo,Jenh-Yih Juang,Shih-Han Tang,Yu-Lun Chueh,Chih Wei Luo,Kaung-Hsiung Wu,Jia-Xing Li

doi:10.1038/srep18354

Abstract

In this work, we demonstrated a viable experimental scheme for in-situ probing the effects of Au nanoparticles (NPs) incorporation on plasmonic energy transfer in Cu(In, Ga)Se2 (CIGS) solar cells by elaborately analyzing the lifetimes and zero moment for hot carrier relaxation with ultrabroadband femtosecond pump-probe spectroscopy. The signals of enhanced photobleach (PB) and waned photoinduced absorption (PIA) attributable to surface plasmon resonance (SPR) of Au NPs were in-situ probed in transient differential absorption spectra. The results suggested that substantial carriers can be excited from ground state to lower excitation energy levels, which can reach thermalization much faster with the existence of SPR. Thus, direct electron transfer (DET) could be implemented to enhance the photocurrent of CIGS solar cells. Furthermore, based on the extracted hot carrier lifetimes, it was confirmed that the improved electrical transport might have been resulted primarily from the reduction in the surface recombination of photoinduced carriers through enhanced local electromagnetic field (LEMF). Finally, theoretical calculation for resonant energy transfer (RET)-induced enhancement in the probability of exciting electron-hole pairs was conducted and the results agreed well with the enhanced PB peak of transient differential absorption in plasmonic CIGS film. These results indicate that plasmonic energy transfer is a viable approach to boost high-efficiency CIGS solar cells.

Highlights

Photovoltaics have been touted as a prominent candidate for solving energy crisis and greenhouse effect
By elaborately analyzing the lifetimes and zero moment for hot carrier relaxation based on the data obtained by ultrabroadband femtosecond pump-probe spectroscopy, we demonstrated that the plasmonic energy transfer in Cu(In, Ga)Se2 solar cells incorporated with Au nanoparticles (Au-NPs) could be probed in-situ
The non-equilibrium carriers can be immediately generated while the pumping pulses excite the semiconductors and their ultrafast relaxation processes reflected from the transient differential absorption signals Δ A were recorded by each probing pulse (see Fig. 1(b))

Summary

Introduction

Photovoltaics have been touted as a prominent candidate for solving energy crisis and greenhouse effect. By elaborately analyzing the lifetimes and zero moment for hot carrier relaxation based on the data obtained by ultrabroadband femtosecond pump-probe spectroscopy, we demonstrated that the plasmonic energy transfer in Cu(In, Ga)Se2 solar cells incorporated with Au-NPs could be probed in-situ.

Results

Conclusion