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[Hiroshi Mizoguchi](https://orcid.org/0000-0002-0992-7449), [Satoru Matsuishi](https://orcid.org/0000-0001-8905-0255), [Hiroyo Segawa](https://orcid.org/0000-0002-7198-8410), [Noriko Saito](https://orcid.org/0000-0002-8104-0172), [Hideo Hosono](https://orcid.org/0000-0001-9260-6728)

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[Valence Band Modulation Using Cationic Filled p Orbitals toward p-Type Conduction](https://mdr.nims.go.jp/datasets/299eb35f-6efa-4bf5-91d3-2606c3cadcff)

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Valence Band Modulation Using Cationic Filled p Orbitals toward p-Type ConductionValence Band Modulation Using Cationic Filled p Orbitals towardp‑Type ConductionHiroshi Mizoguchi,* Satoru Matsuishi, Hiroyo Segawa, Noriko Saito, and Hideo Hosono*Cite This: Cryst. Growth Des. 2025, 25, 1892−1896 Read OnlineACCESS Metrics & More Article Recommendations *sı Supporting InformationABSTRACT: p-Type conduction is difficult in wide-gap compound semi-conductors, such as transparent oxides. Anionic p orbitals primarily constitutingthe valence band maximum (VBM) are localized owing to their highlyelectronegative nature, which gives rise to a large ionization potential (Ip),leading to a difficulty in hole doping into the VBM. Here, we report a newapproach to VBM modulation through the covalent interaction with filled cationicp orbitals. LaN is taken as an example. Pushing the anionic valence band (VB) toVBM by σ interaction in N−La chains between the N 2p VB and the filled La porbitals decreases Ip and enhances the dispersion of VBM, leading to a direct-typeband gap. Cationic p states (La 5p6) located energetically near the VB and linearcoordination of La−N chains present in rock-salt-type crystal structures are keys tomaking the N p−La p covalent interaction strong.■ INTRODUCTIONTransparent oxide semiconductors (TOSs) are attractingmuch attention as thin film transistor channels for drivingflat panel displays and transistors for high-power applicationswith high mobility, good durability, large band gap, and lowproduction cost. The representative examples for applicationsare amorphous indium gallium zinc oxide for the backplane todrive flat panel displays and Ga2O3 single crystals for powertransistors.1−3 However, the conduction type of TOSs ispractically restricted to the n-type, which is a major obstacle toextending the applications of TOSs. This difficulty primarilycomes from the intrinsic nature of large band gap ioniccompounds; i.e., the nature of the valence band maximum(VBM) is to work as the hole pathway, whereas the conductionband minimum (CBM) serves as the electron pathway.Oxygen 2p orbitals primarily constituting the VBM arelocalized owing to the high electron negativity of oxygen andthe absence of other orbitals of nearby cations shownschematically in Figure 1a, which are rather different fromthe spatially extended vacant cationic orbitals constituting theCBM. Consequently, the ionization potential ((Ip), E(VBM)− E(Vac)) is large, whereas the electron affinity (E(CBM) −E(Vac)) is small. Such a large Ip makes it difficult to dopepositive holes into VBM, and a large effective mass of holes atVBM suppresses the mobility of the doped holes.4a,b These arethe general reasons why p-type conduction is difficult in wide-gap ionic compounds such as TOSs. Figure 1b−d summarizesthe approach to p-type TOSs reported to date. The p orbitalshave directional and ungerade symmetry, which makes themless likely to interact with the surrounding orbitals and formcovalent bonds. In particular, 2p orbitals are considerablycontracted among np orbitals (principal quantum number, n =2−6). In the periodic table, orbitals with the smallest numberof n are significantly contracted. To overcome this obstacle, inthe electronic structure design of p-type TOSs, it is oftenaimed to increase the VB dispersion by giving them covalentbonding characteristics. For example, in SnO, the Sn2+ 5s2orbital, called the cationic lone pair, is utilized. The Sn 5s statehaving stereochemical activity is located at about the sameReceived: January 6, 2025Revised: February 24, 2025Accepted: February 25, 2025Published: March 4, 2025Figure 1. VB modulation by the addition of covalent interactions inTOSs. (a) Post-transition-metal oxides commonly have VB composedof oxygen 2p orbitals. (b−e) VB modulation through covalentinteraction with filled cationic bands, which pushes up the VBM.Articlepubs.acs.org/crystal© 2025 The Authors. Published byAmerican Chemical Society1892https://doi.org/10.1021/acs.cgd.5c00012Cryst. Growth Des. 2025, 25, 1892−1896This article is licensed under CC-BY 4.0Downloaded via NATL INST FOR MATLS SCIENCE (NIMS) on March 19, 2025 at 07:26:48 (UTC).See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroshi+Mizoguchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Satoru+Matsuishi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroyo+Segawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Noriko+Saito"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hideo+Hosono"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.cgd.5c00012&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?goto=articleMetrics&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?goto=recommendations&?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?goto=supporting-info&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=tgr1&ref=pdfhttps://pubs.acs.org/toc/cgdefu/25/6?ref=pdfhttps://pubs.acs.org/toc/cgdefu/25/6?ref=pdfhttps://pubs.acs.org/toc/cgdefu/25/6?ref=pdfhttps://pubs.acs.org/toc/cgdefu/25/6?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig1&ref=pdfpubs.acs.org/crystal?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://doi.org/10.1021/acs.cgd.5c00012?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://pubs.acs.org/crystal?ref=pdfhttps://pubs.acs.org/crystal?ref=pdfhttps://acsopenscience.org/researchers/open-access/https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/energy level as that of the 2p O state, and the two interactstrongly to give rise to VB dispersion.5a,b In Cu2O or CuAlO2,an increase in O 2p band dispersion is achieved by hybridizingshallow cationic d orbitals (Cu 3d10).6 In ZnO, the VBM ismodulated by filled Zn 3d10 states that locate at an energy levelclose to that of O 2p VB.7 This is enhanced also by a shortdistance dZn−O in the tetrahedral coordination. Occupied S-states such as s2 or d10 have zero orbital angular momentum.Such an orbital with an isotropic and gerade phase in cationshas relatively easy interaction with the contracted anionic 2porbitals as well. Here, we propose a novel approach todesigning p-type TOSs by utilizing the filled p orbitals ofcations. To embody this concept, we set the following tworequired conditions. (1) A crystal structure having metal cation(M)−anion (X) chains: The M p−X p σ interaction dependshighly on the angle θ (Scheme 1) showing a maximum at θ =180°. (2) We select occupied cationic np6 states having anenergy level slightly deeper than that of oxygen 2p. Thecovalent interaction between these states pushes up the VBconstituted by anion 2p, as shown in Figure 1e. This generatesa rock-salt-type crystal structure, MX (Figure 2a), which meetsboth requirements. In the structure, MX6 octahedra share theedges with each other to form an M−X chain running alongthe a, b, or c direction. Here, we focus on cubic LaN on thebasis of its characteristic VB structure elucidated through DFTcalculations and experiments.■ EXPERIMENTAL SECTIONDFT periodic calculations for the survey of compounds with the rock-salt-type crystal structure (MN with M = Sc, Y, La, or Ce and MOwith M = Ca, Sr, or Ba) were performed using the generalizedgradient approximation and spin orbit coupling as implemented inVASP.8a,b We used the HSE06 hybrid functional9a,b for structuraloptimization, electronic bands, and optical absorption spectrumcalculations. No Hubbard term was taken into account for the 4fstates of La or Ce. All of the calculations were performed with theprimitive cell obtaining one chemical formula, MO or MN. A kineticenergy cutoff of 520 eV with a 6 × 6 × 6 Γ-centered k-point mesh anda cutoff of 400 eV with a k-path of 2.5 Å point density wererespectively used for structural optimization and electronic bandcalculation. The irreducible representations of plane wave-basedspinor wave functions at high symmetry points in the double spacegroup10 were determined using the Irvsp code.11 The Wigner−Seitzradius (Rwigs) for site projections for all atoms was selected to satisfythe equation V = N · 4/3 πRwigs,3 where V is the volume of the unitcell and N is the total number of atoms in the unit cell. To assist inunderstanding the nomenclature of the reciprocal space, the Brillouinzone of the cubic F-lattice is shown in Figure S1 in the SupportingInformation.The band alignment of MN relative to the vacuum level wasobtained using the electrostatic potential calculated with the (100)slab model without surface relaxation, consisting of the nine MNatomic layers (thickness ∼20 Å) and a vacuum space of ∼25 Å.A polycrystalline sample of LaN was synthesized by solid-statereactions at high temperatures. The starting material used was theLaN (99.9%) powder purchased from AlfaAesar. The nitride washeated to 1023 K for 10 h under ammonia. The resulting brownishblack powder was air-sensitive. The crystal structures of thesynthesized materials were examined by powder X-ray diffraction(RIGAKU MINIFLEXII) using Cu Kα radiation. The X-ray data werecollected in the range 2θ = 5−90° at 0.02° intervals at roomtemperature. The obtained powder XRD pattern indicates that LaNhas a cubic rock-salt-type crystal structure, as shown in Figure S2.UV−vis-NIR diffuse reflectance data were collected in the spectralrange of 240−2600 nm with a Shimadzu SolidSpec-3700spectrometer using MgO as a reference. The Kubelka−Munk functionwas used to transform the data into absorbance.■ RESULTS AND DISCUSSIONFirst, Figure S3 shows the calculated band structures of thealkaline earth oxide MO (M = Ca, Sr, or Ba). The bindingenergy (E = 0) is referenced to the VBM. The O 2py orbital ishighlighted in red with a fat-band representation. All threecompounds have large band gaps, and BaO has the smallestband gap (Eg = 3.0 eV) among the three. Whereas thesecompounds with a highly ionic bonding nature often adopt therock-salt-type crystal structure, the band dispersion in the kspace is seen for CBM and VBM. This result means that theparticipation of the covalent bonding nature is not negligiblysmall even in these ionic compounds. The CBM is located atthe X point in these oxides. The widespread band near CBMoriginates from M nd orbitals, and the alkali earth ion Mbehaves like an early transition metal ion. On the other hand,the VB is mainly composed of O 2p, and the bandwidthdecreased in the order of CaO, SrO, and BaO. CaO or SrOwith VBM at the Γ point has an indirect-type band gap.Interestingly, the O 2py band in BaO is pushed up at the Xpoint to form VBM, resulting in the direct-type band gap. TheO 2p band splits into two at the X point, (0 1 0), owing to thesymmetry. One is O 2py; the other is degenerated O 2px 2pz.Although the O 2py band locates at −2 eV from the VBM inCaO, it shifts to the VBM (E = 0 eV) in BaO. Next, Figure S4shows calculated band structures of MN (M = Sc, Y, La, or Ce)nitrides. MN (M = Sc, Y, or La) is a semiconductor, and LaNhas the smallest band gap (Eg = 0.59 eV) among the three.Interestingly, the calculated band gap of LaN is much smallerthan the experimental one of La2O3 (Eg = 5.2 eV). Thecalculated indirect-type band gap of ScN (0.87 eV) isconsistent with the experimental value (0.92 eV).12 Thelarge dispersion of CBMs in these nitrides is very similar tothat in MOs, and the M3+ ion also behaves similarly to a d-block ion. Unoccupied La 4f orbitals locate at ∼+7 eV to formnarrow bands. VB in MNs is mainly composed of the N 2pband, and the bandwidth decreases from that of ScN to that ofLaN through YN. ScN or YN with VBM at the Γ point has theindirect-type band gap. Interestingly, in LaN, the N 2py band ispushed up at the X point to form VBM, resulting in the direct-type band gap, as seen in BaO. The behavior of N 2p bands atScheme 1. M p−X p ChainFigure 2. (a) Crystal structure of LaN (rock-salt-type, lattice constanta = 5.30 Å). (b) Calculated positions of VBM and CBM for MN (M =Sc, Y, or La).Crystal Growth & Design pubs.acs.org/crystal Articlehttps://doi.org/10.1021/acs.cgd.5c00012Cryst. Growth Des. 2025, 25, 1892−18961893https://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=sch1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=sch1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig2&ref=pdfpubs.acs.org/crystal?ref=pdfhttps://doi.org/10.1021/acs.cgd.5c00012?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asthe X point is the same as that of O 2p in the MO series.Although CeN has a metallic nature because of the uniqueelectronic configuration of the Ce3+ ion (5d14f0),13 thebehavior of N 2py band in CeN is similar to that of LaN.Figure 2b shows the calculated VBM and CBM positions forMN (M = Sc, Y, or La). The position of the VBM in LaN ishighly pushed up among the three, indicating the decrease inIp. The results of the survey of MO and MN series exhibit thefollowing two tendencies for VB: With the principal quantumnumber n, (1) the VB width decreases because of the increasein ionic bonding characteristic of Mn+−Xn− interaction, and (2)the anion py band is largely pushed up at the X point to formVBM, resulting in the direct-type band gap.To reveal the implications of the bonding interaction, weexamined the band structure of LaN (Figure 2a) in greaterdepth. Figure 3a shows the details of the band structure again.The La 5py orbital is highlighted in blue with a fat-bandrepresentation. Most of the features of the calculated bandstructure agree well with the previous reports.14a−f Asemiconductor with the direct-type band gap at the k positionexcept for the Γ point is very rare. Figure 4a shows schematicsof orbital interactions of LaN at the CBM and VBM at the Xpoint. The CBM, which does not contain the contribution ofanion orbitals, is deepened by the direct La t2g−La t2g covalentinteraction. In the crystal structure, LaN6 octahedra shareedges with each other, resulting in the shorter distance dLa−La.A smaller lattice arising from a shorter M−M separationenhances the d−d bonding as well, as seen in CeN with ∼5.0 Å(Figure S4d). On the other hand, the behavior of VB is morecomplicated. The band is mainly composed of three N 2porbitals. At the X point, the N 2py band is pushed up to formVBM by its covalent interaction with La 5py (blue fat-band) inthe La−N chain, as shown in Figure 4a. This VB modulation issimilar to that in ZnO caused by the O 2p−Zn 3d covalentinteraction (Figure 1d). From Figure S4c, the 5p bands in LaNlocate at a relatively shallow position (E ∼ −15 eV), makingthe interaction with the VB composed of N 2p possible. Thesemicore-like 5p bands split into p3/2 and p1/2 owing to thespin orbit interaction (SOI). On the other hand, 2p bands oflight N do not split owing to the small SOI, which isproportional to Z4 (Z: atomic number). However, the 2pbands are split weakly by covalent interaction with the split La5p. As shown in Figure S 4d, the modulation of the N 2py bandin CeN is larger than that in LaN, reflecting a stronger SOI ofCe rather than La. The appearance of the direct-type band gapof LaN originates from the peculiar behavior of the N 2pyband. Here, we compare the behavior of N 2py in LaN withthat in ScN having indirect-type band gap to clarify themodulation into the N 2py band. Although the N 2py band atthe X point is located at −3 eV in ScN (Figure S4a), it shiftsconsiderably to VBM (E = 0 eV) in LaN. Sc 3p bands locate at−29 eV (not shown in Figure S4a), which is too deep tointeract with VB. Instead, a direct N 2p−N 2p covalentinteraction works in ScN with a smaller lattice (dN−N = 3.14 Åin ScN). Figure 4b shows the orbital interaction of the A (Γ)point and B (X) point in ScN, shown in Figure S4a. Weak N2py−N 2py σ* antibonding and weak σ bonding work at the Γand X points, respectively, which are not N−N linear chain.That is why the VB width is dominated by the direct N 2p−N2p interaction (dN−N = 3.14 Å) in ScN. On the other hand, theN−N interaction seen in ScN does not work in LaN with alarger lattice (dN−N = 3.75 Å). Instead, semicore-like La 5pbands modulate VB to form a direct-type band gap. Theirreducible representations (irreps) of the VBM and CBMstates at the X point are determined to be X6− and X7+,respectively. The direct product of X6− and the irrep X4− of theelectric dipole operators with the Eu characteristic (x, y) isX7+,15 indicating that the transition between VBM and CBM isallowed. Figure 3b shows the calculated optical absorption ofLaN near the band gap. It stands up steeply near 0.6 eV. Thedirect allowed band gap was experimentally estimated to be0.90 eV from the (hνα/S)2−hν plot (S: scattering coefficient)in the inset of Figure 3b, which is consistent with thecalculated band gap. The observed weak absorption near 0.5eV originates from free carriers in CB, probably induced by a Ndeficiency. This agrees with the formation enthalpy of Nvacancy14f calculated by Deng and Kioupakis.Figure 3. (a) Band electronic structure of LaN. The contributionfrom the La py orbital is highlighted with a fat-band representation inblue. (b) Calculated absorption spectrum near the band gap for LaN.Inset: diffuse reflectance spectra.Figure 4. (a) Orbital interactions at the CBM or VBM in LaN. (b)Orbital interactions at VB in ScN, shown in Figure S4a. One of thethree degenerated N 2p bands is shown for point A.Crystal Growth & Design pubs.acs.org/crystal Articlehttps://doi.org/10.1021/acs.cgd.5c00012Cryst. Growth Des. 2025, 25, 1892−18961894https://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig4&ref=pdfpubs.acs.org/crystal?ref=pdfhttps://doi.org/10.1021/acs.cgd.5c00012?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asThe DFT calculation results for rock-salt-type compoundsexhibit that the filled 5p bands of Ba, La, or Ce modulate VB.This finding forms the basis of the concept applicable to thefine-tuning of the VB design of TOSs. First, we discuss thereason these bands can modulate anionic VB. Can we extendthis concept into np bands of other heavy metal cations?Figure 5 shows the reported energy level of semicore-like npstates of the fifth or sixth period atoms, which was calculatedfor the ground electronic configuration in the local densityapproximation.16 Those of anionic 2p states are also shown toestimate the energetic overlap (ΔE) with the p states of heavymetal elements, which reflects the covalent interaction. Theincreased valence charge of an element makes the energy leveldeeper monotonically. For example, Br 4p bands often locatein the VB region near the Fermi energy in bromides. The 4plevel deepens in the order of Br, Kr, Rb, Sr, and Y. The energylevel of Y 4p states is too deep to interact with anionic 2p VBin the MN nitride. Thus, the cations residing in the left-sideregion of the periodic table have shallow np states. In the sixthperiod shown by a black line, the effect of lanthanidecontraction also occurs. Figure 5 suggests that the shallowfilled np bands of Cs, Rb, Ba, La, Ce, or Pr (Th) can modulateVB.The N 2p−La 5p interaction observed in LaN does notcommonly appear in the electronic structures of inorganicsolids. In fact, it gives rise to a unique direct-type band gap thatappears at the X point owing to the ungerade characteristic ofN 2p orbitals. Finally, we discuss an example of similarsemiconductors that utilize the contribution of cationic pstates. Perovskite (PV)-type halides including CsSnI3 oftenhave the direct-type band gap at the R point for cubic primitivelattices, and they have been anticipated to be used as opticalabsorbers for solar cells.17 A cubic PV-type structure iscomposed of a three-dimensional framework of corner-sharingSnI6 octahedra, with the Cs+ ions filling the cuboctahedralcavities. The I ions are linearly coordinated by two Sn atoms toform a chain, as seen in LaN. The top of VB is dominated bythe contribution of I 5p hybridized by Sn 5s. CBM isdominated by the contribution of Sn 5p hybridized weakly by I5s, as shown in Figure S5.17,18 The top of the CB is composedof the Sn 5p−I 5p σ* interaction in the Sn−I chain, which isvery similar to the VBM of LaN. Thus, the unique positions ofband edges in the k space are derived from the ungeradesymmetry of the p orbitals. The PV halide layer sandwiched byelectron and hole transport layers has been investigated asoptical absorbers for solar cells, where photoexcited carriers areseparated without recombination.19 The high mobility ofexcited electrons originating from the widespread CB renderselectron transport into n-type electrodes possible.■ CONCLUSIONSAnionic p orbitals constituting the VB often do not contributeto covalent bonding in solid compounds because of theirdirectional shape and ungerade symmetry. However, the VBMmodulation of LaN can be achieved through covalentinteraction with filled cationic p bands. A VB structure canbe designed by the careful tuning of the coordination structure,energy level, orbital radius of cationic p states, and SOI. Ingeneral, p-type doping into compound semiconductorsbecomes easier as the Ip decreases. Pushing the VB to VBMby the σ interaction between the anionic np orbitalsconstituting the upper VB and cation’s filled p orbitalsdecreases Ip and enhances the dispersion of VBM, leading tothe reduction in effective hole mass. Thus, this approach willbe a novel way to design p-type semiconductors.■ ASSOCIATED CONTENT*sı Supporting InformationThe Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012.Powder XRD pattern for LaN, the Brillouin zone,electronic structure calculations for MO (M = Ca, Sr, orBa) and MN (M = Sc, Y, La, or Ce), and schematicdensity of states for CsSnI3 (PDF)■ AUTHOR INFORMATIONCorresponding AuthorsHiroshi Mizoguchi − Research Center for MaterialsNanoarchitectonics (MANA), National Institute forMaterials Science (NIMS) Tsukuba, Ibaraki 305-0044,Japan; orcid.org/0000-0002-0992-7449;Email: mizoguchi.hiroshi@nims.go.jpHideo Hosono − Research Center for MaterialsNanoarchitectonics (MANA), National Institute forMaterials Science (NIMS) Tsukuba, Ibaraki 305-0044,Japan; MDX Research Center for Element Strategy,International Research Frontiers Initiative, Institute of ScienceTokyo 4259 Nagatsuta, Yokohama 226-8503, Japan;orcid.org/0000-0001-9260-6728; Email: hosono@mces.titech.ac.jpAuthorsSatoru Matsuishi − Research Center for MaterialsNanoarchitectonics (MANA), National Institute forMaterials Science (NIMS) Tsukuba, Ibaraki 305-0044,JapanHiroyo Segawa − Research Center for Electronic and OpticalMaterials, National Institute for Materials Science (NIMS)Tsukuba, Ibaraki 305-0044, JapanNoriko Saito − Research Center for Electronic and OpticalMaterials, National Institute for Materials Science (NIMS)Tsukuba, Ibaraki 305-0044, Japan; orcid.org/0000-0002-8104-0172Complete contact information is available at:Figure 5. Calculated energy level of filled np state of heavy metalatoms.16 The energy difference (ΔE) between the filled np state andanionic 2p VB is an important factor for the covalent interaction,which results in a large VB dispersion.Crystal Growth & Design pubs.acs.org/crystal Articlehttps://doi.org/10.1021/acs.cgd.5c00012Cryst. Growth Des. 2025, 25, 1892−18961895https://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?goto=supporting-infohttps://pubs.acs.org/doi/suppl/10.1021/acs.cgd.5c00012/suppl_file/cg5c00012_si_001.pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroshi+Mizoguchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-0992-7449mailto:mizoguchi.hiroshi@nims.go.jphttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hideo+Hosono"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-9260-6728https://orcid.org/0000-0001-9260-6728mailto:hosono@mces.titech.ac.jpmailto:hosono@mces.titech.ac.jphttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Satoru+Matsuishi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroyo+Segawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Noriko+Saito"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-8104-0172https://orcid.org/0000-0002-8104-0172https://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.cgd.5c00012?fig=fig5&ref=pdfpubs.acs.org/crystal?ref=pdfhttps://doi.org/10.1021/acs.cgd.5c00012?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://pubs.acs.org/10.1021/acs.cgd.5c00012NotesThe authors declare no competing financial interest.■ ACKNOWLEDGMENTSThe calculations in this study were performed on theNumerical Materials Simulator at NIMS. This work wassupported by a Grant-in-Aid for Scientific Research(23K23440) from the Japan Society for the Promotion ofScience (JSPS). A part of this work was supported by the“Advanced Research Infrastructure for Materials and Nano-technology in Japan (ARIM)″ of the Ministry of Education,Culture, Sports, Science, and Technology (MEXT). ProposalJPMXP123NM5382.■ REFERENCES(1) Nomura, K.; Ohta, H.; Takagi, A.; Kamiya, T.; Hirano, M.;Hosono, H. Room-temperature fabrication of transparent flexiblethin-film transistors using amourphous oxide semiconductors. Nature2004, 432, 488−492.(2) Hosono, H. Exploring Electro-active Functionality of Trans-parent Oxide Materials. Jpn. J. Appl. Phys. 2013, 52 (9R), No. 090001.(3) Oba, F.; Kumagai, Y. Design and exploration of semiconductorsfrom first principles: A review of recent advances. Appl. Phys. Express2018, 11, No. 060101.(4) (a) Robertson, J.; Zhang, Z. Doping limits in p-type oxidesemiconductors. MRS Bull. 2021, 46 (11), 1037−1043. 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