Improved Ultrafast Carrier Relaxation and Charge Transfer Dynamics in CuI Films and Their Heterojunctions via Sn Doping

Abstract

CuI is one of the promising hole transport materials for perovskite solar cells. However, its tendency to form defects is currently limiting its use for device applications. Here, we report the successful improvement of CuI through Sn doping and the direct measurement of the carrier relaxation and interfacial charge-transfer processes in Sn-doped CuI films and their heterostructures. Femtosecond-transient absorption (fs-TA) measurements reveal that Sn doping effectively passivates the trap states within the bandgap of CuI. The I–V characteristics of heterostructures demonstrate drastic improvement in transport characteristics upon Sn doping. Fs-TA measurements further confirm that the CuSnI/ZnO heterojunction has a type-II configuration with ultrafast charge transfer (<280 fs). The charge transfer time of a CuI/ZnO heterostructure is ∼2.8 times slower than that of the CuSnI/ZnO heterostructure, indicating that Sn doping suppresses the interfacial states that retard the charge transfer. These results elucidate the effect of Sn doping on the performance of CuI-based heterostructures.

Directional and Ultrafast Charge Transfer in Oxygen‐Vacancy‐Rich ZnO@Single‐Atom Cobalt Core‐Shell Junction for Photo‐Fenton‐Like Reaction

“…[43] The high TOC removal percentage (76.8 %) of SMX in the ZnO@SA-Co-CN + PMS + Vis system implies its excellent oxidation capacity for decomposing of TrOCs into CO 2 and H 2 O (Figure S17). [44] Besides, the ZnO@SA-Co-CN + PMS + Vis system functions well in a wide working pH range (3)(4)(5)(6)(7)(8)(9)(10)(11), maintaining over 97 % of SMX degradation (Figure 3C). In addition, more than 95 % of SMX can be eliminated after 10 successive cycles of catalytic degradation process (Figure 3D), implying the excellent stability and reusability of the ZnO@SA-Co-CN catalyst.…”

“…The BIEF provides a strong driving force to accelerate charge carriers separation and transfer and to navigate their transportation paths [8] . For example, ultra‐fast electron transfer (<280 fs) from CuSnI to ZnO has been observed in the CuSnI/ZnO p‐n heterojunction via a type‐II charge transfer pathway [9] . The CoFe 2 O 4 /g‐C 3 N 4 p‐n junction improved charge separation and accelerated the Z‐scheme electron transfer from CoFe 2 O 4 to g‐C 3 N 4 (86.99 ps) to boost photocatalytic performance for H 2 evolution [10] .…”

“…[8] For example, ultra-fast electron transfer (< 280 fs) from CuSnI to ZnO has been observed in the CuSnI/ZnO pn heterojunction via a type-II charge transfer pathway. [9] The CoFe 2 O 4 /g-C 3 N 4 p-n junction improved charge separation and accelerated the Z-scheme electron transfer from CoFe 2 O 4 to g-C 3 N 4 (86.99 ps) to boost photocatalytic performance for H 2 evolution. [10] However, the construction of p-n junctions with Z-scheme charge transfer pathways is still challenging and the charge-transfer mechanisms are still not well understood.…”

Impact of laser pulse-width on the nonlinear refractive index of black phosphorus quantum dots

“…Details of our TA measurement can be found in a previous report. 16 2 GW/cm 2 and 30.5 GW/cm 2 , respectively. The OA Z-scan curve shows no peak or valley near the focus, indicating the BP QDs/water dispersions has negligible nonlinear absorption.…”

Directional and Ultrafast Charge Transfer in Oxygen‐Vacancy‐Rich ZnO@Single‐Atom Cobalt Core‐Shell Junction for Photo‐Fenton‐Like Reaction

“…[43] The high TOC removal percentage (76.8 %) of SMX in the ZnO@SA-Co-CN + PMS + Vis system implies its excellent oxidation capacity for decomposing of TrOCs into CO 2 and H 2 O (Figure S17). [44] Besides, the ZnO@SA-Co-CN + PMS + Vis system functions well in a wide working pH range (3)(4)(5)(6)(7)(8)(9)(10)(11), maintaining over 97 % of SMX degradation (Figure 3C). In addition, more than 95 % of SMX can be eliminated after 10 successive cycles of the catalytic degradation process (Figure 3D), implying the excellent stability and reusability of the ZnO@SA-Co-CN catalyst.…”