Design and characterization of InGaP-based InP quantum dot solar cells

Abstract

In an ideal intermediate-band (IB) concept, the host semiconductor generates current by absorbing short-wavelength light and the IB is used to absorb long-wavelength light. Here, we investigate the impact of the host absorber thickness at the front side of the cells on the properties of InGaP-based InP quantum dot (QD) solar cells. We prepared the InGaP-based InP QD cells with the front i-InGaP layer and compared them with the cells without the front i-InGaP layer. The insertion of the front i-InGaP layer results in an increase in quantum efficiency in the visible region, indicating that the short-wavelength light absorbed at the InGaP host increases the short-circuit current density in the cell. In addition, a thick host layer leads to reduced quantum efficiency below the host bandgap energy, which indicates that the thermal escape from QDs is suppressed. These results indicate that the optimization of the host semiconductor thickness is critical for achieving the ideal operation of the IB concept in the QD solar cells.

Dual Junction GaInP/GaAs Solar Cell with Enhanced Efficiency Using Type‐A InP Quantum Wells

“…[30] Two types of QWs (type A and type B) are generally formed using different materials, but experiments also reported the possibility of formation of both types of quantum islands by controlling the size of the wells in the p-i-n region using the same material. [21][22][23] The photon absorption in type-A QW structure is described by thermionic field emission boundary. [31] We have earlier reported GaInP SJ solar cell with type-A InP QWs with enhanced efficiency of 22.41%.…”

“…The experimental studies have reported surprising behavior of InP QWs, as it forms both types of energy band structures (type A and type B) depending on the size control of the wells, as described in literature. [21][22][23] The InP QW is inserted in the p-i-n region, which is a basic phenomenon of QW design, and type-A band structure is shown in Figure 5. Two-step photon absorption takes place in the type-A QW, and carriers are transported through the thermionic field emission process.…”

“…[20] The long-wavelength photons are absorbed by these QWs, and carrier transport is enhanced, which increases the I sc while maintaining the V oc using voltage preservation technique. [21][22][23][24] A dual multiple QW for GaInP/GaAs DJ solar cell is fabricated by MOVPE growth process for enhanced photon coupling. [25] The QWs are also used in tunnel junctions to enhance peak tunneling current.…”

Analytical Model of InP QWs for Efficiency Improvement in GaInP/Si Dual Junction Solar Cell

“…[ 33 ] Insertion of front i‐GaInP layer in type‐A InP QD SC increases the short circuit current ( I SC ) by absorbing the long wavelength light. [ 34 ] Both type‐A and type‐B InP quantum islands have been shown via photo luminescence (PL) spectra, which are coherently strained without any dislocations. [ 35 ] The InGaAs/GaSb ratchet band in IBSC maintains the open circuit voltage by reducing the recombination.…”

“…[ 37–39 ] The InP has an advantage that it has lower bandgap compared to GaInP material, size control, and formation of two distinct band structures using InP nanostructure on GaInP in the previous experiments. [ 34–36 ]…”