Pressure-induced bandgap engineering and photoresponse enhancement of wurtzite CuInS₂ nanocrystals

Abstract

Wurtzite CuInS2 exhibits great potential for optoelectronic applications because of its excellent optical properties and good stability. However, exploring effective strategy to simultaneously optimaze its optical and photoelectrical properties remains...

The NiO/CuInS2 Quantum Dots/ZnO Orderly Nanoarrays Transparent Pn Junction Towards Enhanced Photovoltaic Conversion via Dual Functional CuInS2 QDs

“…[ 36 ] The CuInS 2 QDs obtains an adjustable bandgap, and have been regulated to an appropriate value of 2.344 eV (Figure S1, Supporting Information), so that can balance the solar efficiency and potential transition. [ 47–49 ] However, due to the low concentration, the introducing of narrower band gap CuInS 2 QDs would influence the transparency less, and corresponds to the insert photo, such clear figure manifests that the as‐prepared transparent pn junction can be competent for practical windows. Significantly, the increasing of photovoltaic performance is more obvious than the slight decreasing of transparency, which indicates that, the CuInS 2 QDs with high QY and Fermi level transition can play more crucial roles than simple absorption increasing during the photovoltaic process.…”

“…[ 19–21 ] Additionally, a mass of nanoparticles are deposited at the pn junction interface and surface of ZnO nanorod (Figure 4a). There, the corresponding lattice spacing of 0.321 nm is attributed to the (111) plane of CuInS 2 (Figure 4c), [ 47–49 ] and indicates the presence of CuInS 2 QDs.…”

“…[ 19,20 ] The peaks at 931.52 and 951.38 eV are attributed to the Cu 2p (Cu + , Figure 5b), and the peaks at 444.30 and 451.83 eV are attributed to the In 3d (In 3+ , Figure 5c), those manifest the successfully introducing of CuInS 2 QDs. [ 47–49 ] Additionally, the peaks at 853.61 and 870.74 eV are attributed to the Ni 2+ ions, and the peaks at 855.58 and 872.36 eV are attributed to the Ni 3+ ions caused by Ni vacancy, which is an important reason for enhanced p‐type conductivity. [ 35–37 ] It is significant that, the Ni 2+ /Ni 3+ mixed state can induce the formation of hole‐related carrier to improve p‐type conductivity further.…”

“…Demonstrated as transparency and photovoltaic performance, the as‐prepared NiO/ZnO‐CIS‐2 obtains obvious photovoltaic enhancement (≈2.5 × 10 3 folds), whereas a slight transparency decreasing (≈3–5%), which manifests that the Fermi levels transition and carrier injection of CuInS 2 QDs would play more important roles. [ 30,45,54 ] Herein, the CuInS 2 QDs between interfaces can act as stair to accelerate carrier transferring, others deposited on ZnO nanorods surface can act as donor to increase photogenerated carrier injection, [ 48,49 ] while maintaining a high transparency via its intrinsic adjustable wide band gap. Additionally, CuInS 2 QDs can induce Ni vacancy to increase the Ni 2+ /Ni 3+ ions, [ 30 ] which can increase p‐type conductivity to enhance the photovoltaic performance further.…”

“…[ 44 ] Herein, the transition layer modification has attracted lots of attentions, because which can decrease the potential gradient to regulate potential structure, [ 45,46 ] while accelerating charge carrier transportation via interface modification. Especially the CuInS 2 quantum dots, [ 47,48 ] besides depended on itself size, the bandgap, and potential can also be regulated by the ratio of Cu/In, which can provide more larger range for matching the pn junction potential gradient, such as Li and groups have used CuInS 2 nanocrystals to improve the photoresponse, [ 49 ] Peng and groups have improved the charge transfer property of solar cells via CuInS 2 /CdS QDs, [ 50 ] and so on. Additionally, the presence of Cu vacancy would induce the Ni injection to increase the Ni vacancy, [ 51,52 ] which can increase the Ni 3+ ions to increase p‐type conductivity.…”