Orientation Engineering in Low‐Dimensional Crystal‐Structural Materials via Seed Screening

Abstract

CuSbSe 2[15] solar cells were also rapidly developed with PCE over 4%. However, caused by asymmetric atom coordination, the LDCS materials exhibit significantly anisotropic carrier transport in different orientations (Figure 1a,b). Along the covalent bond direction (the chain and the layer directions of 1D and 2D materials, respectively), the overlapping electron clouds are beneficial to the carrier transport ( Figure 1c, right part). Whereas, the carriers have to undergo interchain or interlayer barriers when transport perpendicular to covalent bond directions (Figure 1c, left part). [6a] Typically, the anisotropic factor of mobility, conductivity or effective mass of LDCS materials can reach 10-100 in different directions. [16] At present, orientation control is an urgent problem for LDCS-based semiconductor devices.However, ruled by the minimum energy principle, orientation control is intrinsically difficult for LDCS materials. In brief, materials are prone to grow with low-energy crystal faces parallel to the substrates when deposited under an equilibrium state. For LDCS materials, the crystal faces parallel to the direction of van der Waals (vdW) force (e.g., the side faces of 1D materials and layer faces of 2D materials) always demonstrate lower surface energy than those along covalent bond directions (Table S1, Supporting Information). [6a,17] Therefore, the chains or layers are prone to lying on the substrates, implying photogenerated carriers must hop against interchain or interlayer barriers from the bottom electrode to top electrode (Figure 1a-c), causing transport difficulty. The dependence of orientation on the PCE of solar cells are solidly verified by Sb 2 Se 3 , CuSbSe 2 and SnS solar cells, even the low-dimensional organic-inorganic hybrid perovskite solar cells (e.g., quasi-2D (MAPbI 3 ) 3 BA 2 PbI 4 , here MA = CH 3 NH 3 + , BA = C 4 H 13 NH 3 + ). [18] Generally, the suitable orientation ([hkl, l ≠ 0] orientations for 1D materials and [hk0] orientations for 2D materials, where we define Miller indices l of 1D and 2D materials is along the chain direction and perpendicular to the layers, respectively) is able to promote the carrier collection and reduce the series resistance of solar cells, resulting in the improvement of photocurrent and fill factor (FF) of LDCS-based solar cells.In 2015, the preferentially [211]-and [221]-oriented Sb 2 Se 3 solar cells were fabricated on CdS buffer layer through The orientation of low-dimensional crystal-structural (LDCS) films significantly affects the performance of photoelectric devices, particularly in vertical conducting devices such as solar cells and light-emitting diodes. According to film growth theory, the initial seeds determine the final orientation of the film. Ruled by the minimum energy principle, lying (chains or layers parallel to the substrate) seeds bonding with the substrate through van der Waals forces are easier to form than standing (chains or layers perpendicular to the substrate) seeds bonding with the substrate by a covalent bond. ...

Recent Advances in 2D Metal Monochalcogenides

“…Nevertheless, to date there are limited studies on such interlayer optical and electronic responses. [254][255][256][257][258] Furthermore, the highly anisotropic electrical and optical properties in MMCs integrated with 0D (quantum dots) or 1D organic and/or inorganic and perovskite semiconductor materials could open up a new path for next-generation electronic applications. Overall, the very recent exciting achievements in the field of few-layer MMCs showed a great potential for their application in next-generation electronic, optoelectronic, and emerging nanophotonics, including valley electronics, solar cells, sensors, and nonlinear optical applications.…”

Controlled Sputtering Pressure on High-Quality Sb2Se3 Thin Film for Substrate Configurated Solar Cells

“…where I(hkl) and I0(hkl) are the diffraction peak intensities of (hkl) planes in the measured and standard XRD pattern of Sb2Se3 (JCPDS 15-0861), respectively. Large TC value of a diffraction peak indicates preferred orientation along this particular direction [26]. As can be seen from the figure, the mixed-Sb2Se3 sample shows the highest overall TC values for the (hkl, l≠0) planes and the lowest TC values for the (hk0) planes among all the samples, indicating the optimal growth orientation of the film.…”

“…All the samples demonstrate vertical orientations, as evidenced by the prominent diffraction peaks of (211) and (221). Texture coefficients (TC) of the diffraction peaks were calculated using the equation below to quantitatively investigate the orientation preference (Figure 4b) [26]: It is well known that film orientation plays as an essential role in the photovoltaic performance of Sb 2 Se 3 thin film solar cells. Reports have shown that transport of photogenerated carriers would be facilitated within the bulk film once the Sb 2 Se 3 grains are in vertical orientations, as the carriers could travel readily within the covalently bonded ribbons in this case.…”

“…All the samples demonstrate vertical orientations, as evidenced by the prominent diffraction peaks of (211) and (221). Texture coefficients (TC) of the diffraction peaks were calculated using the equation below to quantitatively investigate the orientation preference (Figure 4b) [26]:…”

Over 7% Efficiency of Sb2(S,Se)3 Solar Cells via V‐Shaped Bandgap Engineering

“…Among them, antimony chalcogenide thin‐film solar cells, including Sb 2 Se 3 , Sb 2 S 3 , and Sb 2 (S,Se) 3 alloy, have been developed rapidly in recent years. Sb 2 Se 3 solar cells based on superstrate configuration have achieved over 7.6% efficiency by vapor transport deposition (VTD) and rapid thermal evaporation (RTE) method . Simultaneously, the record efficiency of 9.2% of substrate configuration Sb 2 Se 3 solar cells has been obtained by constructing a nanorod array via a closed‐space sublimation (CSS) method .…”