Integration of planar and bulk heterojunctions in polymer/nanocrystal hybrid photovoltaic cells

Abstract

We present in this communication a hybrid polymer/nanocrystal photovoltaic device architecture wherein a net poly(3-hexylthiophene) (P3HT) light-absorbing film is inserted underneath the blended layer of P3HT and PbSe nanocrystal quantum dots in the active region. Such a design features the vertical integration of planar and bulk heterojunctions, which allows for the employment of a thinner bulk heterojunction for more efficient carrier collection without an excessive reduction of the overall light absorption by the photovoltaic cell. The measured device performance represents a significant improvement over previously reported hybrid cells containing bulk heterojunctions of P3HT and Pb(S,Se) nanocrystal quantum dots.

Polymer selection toward efficient polymer/PbSe planar heterojunction hybrid solar cells

“…After optimization, A remarkably high PCE of 5.31% was obtained for the HSCs based on PDTPBT and PbSe QD synthesized at 160°C (bandgap = 1.43 eV). To the best of our knowledge, this PCE is the highest value reported for the PbSe based HSCs [37,38]. This significant device improvement may be attributed to the careful selection of proper polymer and NC sizes.…”

Efficient Heterojunction Photovoltaic Cell Utilizing Nanocomposites of Lead Sulfide Nanocrystals and a Low‐Bandgap Polymer

“…Therefore, among the hybrid devices fabricated here, the best power conversion efficiency of 3.78% was obtained with the polymer blend film having PbS NCs with the first excitonic peak at 795 nm. We believe that this efficiency is the highest among those hybrid bulk heterojunction cells based on polymer and PbS (or PbSe) NCs reported in the literature 24–31…”

“…Recently, the use of a low‐bandgap polymer with CdSe NCs resulted in power conversion efficiency of 3.2% with a broad absorption spectrum from UV to ∼800 nm 23. To achieve better light harvesting including near‐ and mid‐infrared (IR) wavelengths, PbS and PbSe NCs have been investigated in hybrid polymer solar cells 24–28. While these materials will require appropriate encapsulation and proper disposal to avoid environmental contamination, they represent the best choice of materials for achieving highly efficient nanocrystal based solar cells.…”

Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

“…Current losses in the solar cells by the presence of a shunt resistance are typically due to the current leakage from the edge of the cell, from pinholes in the film or to trapping of charge carriers in deep traps. 47 It has been reported by Tan et al 48 that the low shunt resistance in solar cells with a bulk heterojunction of a conjugated polymer and semiconductor QDs arose from the shunt contact between the electron transporting QDs and the ITO/ PEDOT:PSS anode. They obtained an increase of the shunt resistance and the device performance when a thin layer (10 nm) of P3HT was inserted underneath the P3HT:PbSe blend layer.…”